Title: “C” is for Cookie and “G” is for Geode Abstract: Figure 1. A Brazilian geode shows a striking resemblance to the legendary Cookie Monster character. The intact geode measures 61 mm in length and 40 mm in diameter. Photo by Robert Weldon; courtesy of Mike Bowers.

“C” is for cookie and “G” is for geode. Gemstones are well known for their ability to mimic familiar themes, but the rock that recently launched a thousand online posts resembled one of the most recognizable children’s characters, the Muppet known as the Cookie Monster (figure 1). The uncanny likeness set the internet ablaze with reports from news sources around the globe. A video of the geode featuring Cookie Monster’s signature tune, “C is for Cookie,” was uploaded to Facebook by its owner, gem collector Mike Bowers, on January 16, 2021. The viral clip reached more than one million views just a week later. All the attention left many wondering, “How could a rock like this form?”
The discovery of the Cookie Monster geode, reportedly from Brazil, is a combination of geologic design and pure luck. It is composed of banded layers of microcrystalline quartz, commonly known as agate. The scientific processes required are complex but can be simplified into some general steps (J.D. Winter, Principles of Igneous and Metamorphic Petrology, Pearson Prentice Hall, Upper Saddle River, New Jersey, 2013). This type of geode occurs as a secondary formation when gas bubbles trapped in volcanic rocks, known as vesicles, are filled with silica-rich fluids. Over time, the fluids deposit concentric layers of microcrystalline quartz along the interior of the vesicle. The accumulation of these layers reflects the variation in chemistry and changing conditions of the silica-rich fluid. These fluctuating conditions can result in a banded formation of the microcrystalline quartz, thus giving rise to an agate. The final siliceous fluid in the last stage of formation allowed for a large central druzy quartz–lined cavity that represents the “mouth” of the Cookie Monster (figure 2, left).

Figure 2. This geode was serendipitously cut at a perfect angle, resulting in halves resembling the famous Cookie Monster (left). Coincidentally, the geode also showed blue fluorescence under long-wave ultraviolet light, reminiscent of the character’s blue fur (right). Photos by Robert Weldon; courtesy of Mike Bowers.
Cutting the rock at the perfect angle to reveal such a startling semblance was a matter of sheer chance, for the internal structure of a geode is not known until it is split open. Any slight change in cutting direction might have resulted in viewers not experiencing the phenomenon of pareidolia, the tendency to assign familiar shapes or faces to abstract forms (Winter 2007 Lab Notes, pp. 363–364).

“C” is for Cookie and “G” is for Geode

The color in blue agate is created by scattering of light; when the particles of silica are smaller than 400 nm, blue light is reflected back (G. Rossman, “Cause of color in agate and chalcedony,” Seventeenth Annual Sinkankas Symposium, April 24, 2021). When the rock was exposed to long-wave ultraviolet light, it revealed strong blue fluorescence (figure 2, right) consistent with the fur color of the famous Muppet. Also of gemological interest was a microscopic feature: Below the quartz-lined “mouth” was a small inclusion of yellowish limonite, a hydrous iron oxide, resembling a cookie crumb (figure 3).

Figure 3. A small impurity of yellow limonite resembling a cookie crumb was found under the “mouth” of the Cookie Monster. Photomicrograph by Nathan Renfro; field of view 4.70 mm.
While geodes can be millions of years old, the Cookie Monster character only emerged within the last century. The Cookie Monster, originally created as a prototype in 1966 by Jim Henson, debuted on the American educational children’s television series Sesame Street in 1969. The name was taken from his incessant obsession with the baked goods. With Sesame Street still on the air today, after 51 seasons, Cookie Monster’s fame is sealed in pop culture.
It was a fortuitous circumstance that the formation of the geode resulted in such a remarkable specimen. As GIA analytical microscopist John Koivula likes to say, “Mother Nature cooks in a dirty kitchen.” Who knows what she will cook up next, but one can hope it has us all cracking open a smile once more. Source: GIA @topic:2


Title: Exhibition Review: Gemstone Carvings: The Masterworks of Harold Van Pelt Abstract: Figure 1. Faceted quartz egg. © 2010 Harold and Erica Van Pelt.

World renowned for their gem photography, Harold and Erica Van Pelt are no strangers to beauty, accuracy, and integrity. Harold Van Pelt has applied the same principles to gemstone carving for more than 40 years. Thirty-five of his pieces, including the faceted quartz egg with aquamarine pedestal seen in figure 1, have returned to Santa Ana’s Bowers Museum, where they were first exhibited in 2010. The exhibition, called Gemstone Carvings: The Masterworks of Harold Van Pelt, is located in the PIMCO Foundation Gallery of the Dorothy and Donald Kennedy Wing.

The precision of Van Pelt’s work is apparent even at the entrance of the gallery. Displayed here are three carvings, including a stunning moss agate bowl and an agate rhyton shaped as a ram’s head (figure 2). Along the wall, glass cases show 26 of Van Pelt’s carvings. Some are accompanied by rough crystals of the material used in the carving; a striking amethyst cup with 24 flutes carved into the base and body is placed alongside two rough amethyst crystals (figure 3). A candlestick carved from Australian chrysoprase is shown with a piece of rough that reveals the blue-green gem emerging from the gray rock.

Figure 2. Agate rhyton. © 2010 Harold and Erica Van Pelt.

Figure 3. Amethyst cup with amethyst crystals. © 2010 Harold and Erica Van Pelt.
Quartz eggs are prominent throughout the exhibition, along with instructions and photographs along one wall detailing how to create these pieces. In “Suspension,” one of these hollow eggs is supported by gold over a mahogany obsidian base. The eggs are by no means the only showcase for Van Pelt’s talents. A seemingly delicate quartz container suspended from two pillars of rutilated quartz, called “Balancing Act” (figure 4) shows how much strength the material actually possesses. While quartz is featured in many pieces, other materials used in combination include petrified wood and tourmaline, the latter in a stunning vase.

Figure 4. “Balancing Act.” © 2010 Harold and Erica Van Pelt.
Of particular note are carvings that represent the human anatomy, such as an exquisite reproduction of a skeleton’s hand in white chalcedony. The material was chosen for its resemblance to the color of human bones. Both sides of the piece are visible, and each bone in the hand took months to complete, showing Van Pelt’s attention to even the smallest details of each carving. Similarly, a life-sized recreation of both sides of Erica Van Pelt’s hand in rutilated quartz (figure 5) even captures the shape of her fingernails. A hollow skull carved from quartz with rare izoklakeite inclusions features a jaw that opens and closes (figure 6). Created from a 250 lb. crystal, the finished piece weighs 6.5 lbs. and is named “Izok.”

Figure 5. Rutile hand. © 2010 Harold and Erica Van Pelt.

Figure 6. “Izok.” © 2010 Harold and Erica Van Pelt.
While the exhibition is a must for gem aficionados, Gemstone Carvings is worth a visit for anyone who appreciates beauty and artistic skill.

Gemstone Carvings: The Masterworks of Harold Van Pelt is on exhibit at the Bowers Museum indefinitely. General admission is $13 on weekdays, $15 on weekends. Students and seniors are $10 on weekdays and $12 on weekends; children under 12 are free every day. The Bowers Museum is open Tuesday–Sunday from 10:00 a.m. to 4:00 p.m.; it is closed on Mondays, Thanksgiving, Christmas Day, New Year’s Day, and July 4th. Source: GIA @topic:9


Title: First Discovery of Topazolite in Mexico Abstract: Garnet occurs in a wide variety of colors according to composition: pyrope and almandine (typically red), spessartite (brownish to orange), grossular (brown, yellow, and green), andradite (brown to black), and uvarovite (bright green). The three varieties of andradite are melanite, topazolite, and demantoid. Topazolite, a name that has been criticized as too similar to that of the gem species topaz, is a greenish yellow to yellow-brown andradite. According to some studies (e.g., C.M. Stockton and D.V. Manson “Gem andradite garnets,” Winter 1983 G&G, pp. 202–208), it rarely occurs in crystals large enough to be faceted.

In January 2014, during mineralogical investigations of Mexican garnet, we made the first reported discovery of fine topazolite crystals in Mexico. These yellow to yellow-brown crystals, measuring 1.5–2.5 cm, are hosted by the Las Vigas skarn deposits (the Cerro de la Concordia mine in Las Vigas de Ramirez municipality and the Piedra Parada mine in Tatatila municipality). The deposits are located in Veracruz State, about 50 km southeast of the town of Valle de Veracruz.

The garnet composition was determined by electron microprobe, using a 41-point analysis and standard conditions of 20 kV, 20 mA, and 1 µm beam size on a JEOL JSM-35c microprobe. We chose a euhedral, relatively homogeneous crystal about 1 cm in diameter from the specimen shown in figure 1. Measurement time was 30 seconds on the peak center. The standards used were MgO for Mg, Al2O3 for Al, jadeite for Si, wollastonite for Ca, and elemental Fe and Mn. The electron microprobe analyses showed little compositional variation or zoning. We calculated the structural formula on the basis of 12 oxygen atoms, with the assumption of all iron as ferric. The approximate composition averaged (Ca2.86Mg0.06Mn0.02)2.94(Al1.20Fe3+0.72)1.92Si3.03Ti0.05O12, which may be expressed as Gr60.50And36.70Py2.80.

Figure 1. This topazolite specimen is from a recent discovery in the Mexican state of Veracruz. Photo by Cristobal Castillo.
UV-visible spectroscopy showed absorption bands at 375, 416, 442, 497, and 584 nm, which can be assigned to the spin-forbidden crystal-field transition of Fe3+ substituted on the octahedral Al3+ site of the garnet structure. The correlated set of these bands also show a pattern close to that characteristic of a d5 trivalent ion in octahedral oxygen coordination. The Mössbauer spectra were characterized by a sharp, slightly asymmetric ferrous doublet. The UV-visible and Mössbauer spectra are comparable to those reported for some garnets in previous reports (A.S. Marfunin, Ed., Advanced Mineralogy, Vol. 2, Springer-Verlag, Berlin, 1995, pp. 74–75, 114).

The three samples of rough topazolite (measuring 1.0–1.5 cm in longest dimension) gave the following properties: yellow-brown color; isotropic and weakly anisotropic; weak strain birefringence; RI—nα = 1.84–1.89; hydrostatic SG—3.75–3.85; and fluorescence—inert to both long- and short-wave UV radiation.

This Mexican topazolite deposit has not been mined, and in the absence of detailed geological, mineralogical, and gemological study, no estimate of the reserves is available. For now, there are no specimens or fashioned material from Las Vigas in the Mexican lapidary market. Source: GIA @topic:2


Title: Fascinating Fluid Inclusions in Chinese Ruby Abstract: Figure 1. Fluid inclusion mimicking a snake in Yuanjiang ruby from China (left). The diagram on the right shows the details of this “snake.” Photomicrograph by Wenqing Huang; field of view 0.26 mm.
Gem rubies from the Yuanjiang deposit in Yunnan Province, China, host mineral inclusion assemblages comparable with those in rubies from other marble-hosted deposits (W.Q. Huang et al., “Trace element geochemistry and mineral inclusions constraints on the petrogenesis of a marble–hosted ruby deposit in Yunnan Province, China,” Canadian Mineralogist, Vol. 59, No. 2, 2021, pp. 381–408). Moreover, the fluid inclusion scenes in rubies from all of these deposits are also similar (G. Giuliani et al., “Fluid inclusions in ruby from Asian marble deposits: Genetic implications,” European Journal of Mineralogy, Vol. 27, No. 3, 2015, pp. 393–404).

Figure 2. This Yuanjiang ruby from China contains an interesting fish-like fluid inclusion. Photomicrograph by Wenqing Huang; field of view 0.17 mm.
Two rubies from the Yuanjiang deposit showed several interesting fluid inclusions. The most impressive one strongly resembles a snake raising its head (figure 1). The other mimics a fish (figure 2). As shown in figures 1 and 2, the whole fluid cavity was split into two parts, both of which show a bubble. Raman spectroscopy analysis identified the transparent tabular crystals in the snake as diaspore (figure 1). The “snake” also hosted a solid inclusion of arsenopyrite (FeAsS); the needle on its head could not be characterized by Raman spectroscopy due to its fineness. The fluid composition was dominated by CO2 with minor components such as H2S, COS, and CH4, as revealed by Raman spectra and microthermometry. How these special inclusions formed has been speculated elsewhere (W.Q. Huang, “Fluid inclusion and titanite U–Pb age constraints on the Yuanjiang ruby mineralization in the Ailao Shan–Red River metamorphic belt, southwest China,” Canadian Mineralogist, 2021, accepted). This morphology-forming process has been explained by two mechanisms that evolved step by step. The first is morphological ripening that resulted in negative shapes of fluid inclusions; the second consists of subsequent reactions between the trapped H2O and the host corundum during the cooling of the inclusion, generating a diaspore that segregated the fluid completely.
Inclusions (mostly mineral inclusions) in gemstones that mimic scenery and landscapes are fascinating and relatively common. One novelty inclusion, an interesting “fried egg” of epigenetic residue trapped in a fissure, was recently found in rock crystal quartz (Fall 2020 G&G Micro-World, pp. 430–431). However, such novelty inclusions, especially fluid inclusions mimicking animals, are exceptionally rare. Source: GIA @topic:3


Title: Octahedral Gahnospinel Crystal in Sri Lankan Blue Sapphire Abstract: A greenish blue octahedral crystal of gahnospinel found in Sri Lankan blue sapphire. Photomicrograph by Yusuke Takamura; field of view 3.81 mm.
Recently, the authors encountered a greenish blue octahedral crystal inclusion in a Sri Lankan blue sapphire (see above). Visual features, such as the greenish blue color and octahedral shape, and Raman spectroscopy identified the inclusion as gahnospinel, with the formula (Mg,Zn)Al2O4.
Gahnospinel inclusions in sapphire often suggest a Sri Lankan origin (A.C. Palke et al., “Geographic origin determination of blue sapphire,” Winter 2019 G&G, pp. 536–579). In addition, gahnospinel inclusions with euhedral crystal shape have been reported previously (E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Volume 3, Opinio Verlag, Basel, Switzerland, 2008). This crystal, however, shows large and beautiful octahedral features. Source: GIA @topic:3


Title: Metal Sulfide Crystal in a Sapphire Abstract: A rounded metal sulfide crystal displays a metallic luster within an unheated sapphire. Photomicrograph by Muzdareefah Thudsanapbunya; field of view 2.3 mm.

The author recently examined a faceted sapphire from Sri Lanka. Gemological analysis confirmed that it was unheated. The sample contained a crystal that, when examined under the microscope using darkfield illumination and oblique fiber-optic illumination, exhibited a highly reflective surface. The observations of the metallic luster and rounded appearance (see above) suggested that this inclusion was most likely an iron sulfide.
Iron sulfides are found as opaque mineral inclusions with metallic luster in corundum. The iron sulfides usually seen in corundum are pyrite (FeS2) and pyrrhotite (Fe1-xS) (E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Vol. 3, Opinio Publishers, Basel, Switzerland, 2008, p. 285). Also present was a partially healed fracture, or fingerprint, next to this crystal, which made for an interesting inclusion scene. Source: GIA @topic:3


Title: Spray of Columbite Crystals in Topaz Abstract: Bladed crystals of columbite radiate from a central point in colorless topaz. The mirror-like surfaces allow for reflections of neighboring blades, as seen in the top left crystal. Photomicrograph by Tyler Smith; field of view 2.90 mm.
A probable columbite inclusion in beryl was featured in a recent Quarterly Crystal, demonstrating the striking form these minerals can display (Spring 2023 G&G Micro-World, pp. 90–91). It was only fitting to follow up with a look at the same inclusion hosted by a different mineral.
The cluster of bladed columbite crystals in the figure above, identified via Raman spectroscopy, was found in an 8.91 ct colorless topaz. The thinner crystals allowed the brown bodycolor to show through, while the thicker, sword-like center crystal appeared black and opaque. Thin-film interference was observed between the host and inclusion when illuminated with oblique lighting, adding some welcome color to an otherwise featureless crystal face. While columbite has been previously described in topaz (Fall 2009 G&G Lab Notes, pp. 212–213; E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Volume 2, Opinio Publishers, Basel, Switzerland, 2005, pp. 263, 738), this is the most dramatic example observed by the author. Source: GIA @topic:2


Title: Quarterly Crystal: Ferrocolumbite in Topaz Abstract: Figure 1. This 239.25 ct topaz crystal hosts some interesting inclusions of ferrocolumbite. Photo by Diego Sanchez.

Figure 2. Laser Raman microspectrometry identified the smallest of these inclusions as ferrocolumbite. Photomicrograph by Nathan Renfro; field of view 17.62 mm.
The author recently acquired a 239.25 ct transparent well-formed topaz crystal from the collection of Leon M. Agee. The crystal from the Shigar Valley in Pakistan, shown in figure 1, has a flat base formed by a cleavage plane. The termination appears to be a pyramid form. The crystal plays host to two prominent opaque black inclusions and one smaller similar-appearing inclusion that is close to the surface of the host (figure 2). The two larger inclusions were too deep in the topaz to analyze. However, the small inclusion was near the surface of one of the prism faces and could be reached by laser Raman microspectrometry. Testing showed a very close match to ferrocolumbite (columbite-Fe). Because of the resemblance between the smaller inclusion and the two larger ones, we concluded that the two larger inclusions were also ferrocolumbite. As an interesting aside, these inclusions are reminiscent of star cruisers in the Star Wars anthology. Source: GIA @topic:2


Title: Apatite Cluster in Zambian Emerald Abstract: An inclusion cluster consisting of a hexagonal prismatic apatite crystal and many rod- and bamboo-shaped crystals of apatite in a Zambian emerald. Photomicrograph by Ungkhana Atikarnsakul; field of view 3.60 mm.
This author recently studied a 1.68 ct faceted emerald containing several inclusions, including blocky fluid inclusions, transparent brownish crystals, needles, and particle clouds. These inclusions as well as the trace element chemistry supported a Zambian geographic origin. The emerald also exhibited elongated transparent crystals that resembled amphibole. In this case, Raman spectroscopy confirmed the mineral as apatite. Interestingly, this apatite formed a distinct inclusion cluster consisting of a large hexagonal prismatic crystal (a morphology typical of the mineral) associated with a multitude of rod- and bamboo-shaped crystals in various directions (see above). Other solid crystals observed in Zambian emerald include mica, actinolite (amphibole), quartz, zircon, and chromite.
Apatite, a common phosphate mineral, has previously been reported in various forms and in many other types of gems such as corundum, spinel, feldspar, and garnet, and it is not surprising to find it in emerald. However, this is the first time the author has encountered this fantastic form of apatite in emerald. Source: GIA @topic:2


Title: Zircon in Jadeite Jade Abstract: This doubly terminated tetragonal crystal in jadeite jade was identified as “high” zircon using Raman spectroscopy. Photomicrograph by Tyler Smith; field of view 2.90 mm.

One translucent green bangle bracelet recently examined by the author contained an interesting inclusion. The material was identified as dyed and polymer-impregnated jadeite jade using standard gemological testing and advanced spectroscopy, including UV-Vis, Raman, and infrared. This material would be classified as C-type jade in the trade.
Microscopic examination revealed a surprisingly well-formed transparent brownish crystal inclusion (see above). Raman analysis of the doubly terminated tetragonal prism revealed it to be “high” zircon (ZrSiO4). To confirm this, the full width at half maximum (FWHM) of the internal stretching mode at 1008 cm–1 was calculated as 6.05 cm–1, indicating a high level of crystallinity, as this band is known to broaden as metamictization occurs (L. Nasdala et al., “Metamictization and U-PB isotopic discordance in single zircons: A combined Raman microprobe and SHRIMP ion probe study,” Mineralogy and Petrology, Vol. 62, 1998, pp. 1–27).
Although interstitial zircon grains are not uncommon in jadeites, such a euhedral crystal is rarely observed and is especially unexpected considering the various treatments its host had undergone. Source: GIA @topic:13


Title: Quarterly Crystal: Garnets in Aquamarine Abstract: Figure 1. This aquamarine crystal plays host to several orange garnet crystals. Photo by Angelica Sanchez.

For this quarterly crystal, we examined a transparent light blue-green hexagonal prism of aquamarine beryl terminated with a flat pinacoid (figure 1). The crystal weighed 26.16 ct with corresponding measurements of 25.93 × 11.64 × 9.08 mm. This aquamarine reportedly came from the Shigar Valley in the Skardu district, Gilgit-Baltistan territory of Pakistan, an area known to produce gemmy aquamarine crystals.

Figure 2. The garnets in the aquamarine were identified by Raman analysis as spessartine. Photomicrograph by Nathan Renfro; field of view 9.40 mm.
Magnification revealed numerous intense orange syngenetic garnet crystals near the base of the aquamarine. Raman analysis of the well-formed garnets identified them as spessartine (figure 2).
Garnet inclusions in beryl are rare. Having the opportunity to study this euhedral crystal gives us further insight into the pegmatitic origin of this aquamarine and its locality. Source: GIA @topic:3


Title: Unusually Shaped Rutile Crystal Inclusions in Russian Emerald Abstract: Figure 1. This long yellowish brown rod was identified by Raman spectroscopy as rutile. Photomicrograph by Charuwan Khowpong; field of view 1.75 mm.

Russian emeralds have been mined since the mid-nineteenth century near Yekaterinburg in the Ural Mountains. They are classified as schist-related emeralds, meaning they formed in the reaction zone of a pegmatite intruding into schists. Similar emeralds are found in Zambia, Brazil, and Ethiopia. All of these deposits can show a similar inclusion scene (S. Saeseaw et al., “Geographic origin determination of emerald,” Winter 2019 G&G, pp. 614–646).

Figure 2. The group of disordered coarse needles of rutile. Photomicrograph by Charuwan Khowpong; field of view 3.65 mm.
A 1.489 ct Russian emerald crystal collected by GIA at the Mariinsky Priisk mine showed several interesting included crystals. The crystals appeared as long yellowish brown rods (figure 1). In some cases, they appeared as a group of disordered coarse needles (figure 2). They were identified by Raman spectroscopy as rutile. Although rutile crystal inclusions are common in schist-related emeralds, this crystal morphology is unusual and has not previously been mentioned in the literature. Therefore, this inclusion might be unique and different from the other schist-related emerald sources. These unusual patterns could potentially be an indicator of Russian origin. Source: GIA @topic:3


Title: Quarterly Crystal: Triplite in Topaz Abstract: Figure 1. A pinkish orange inclusion dominates the interior of this 20.58 ct unpolished topaz crystal from Pakistan. Photograph by Kevin Schumacher.

	The transparent colorless 20.58 ct topaz crystal in figure 1 clearly hosts a prominent translucent pinkish orange inclusion. The topaz, from Biensa in Braldu Valley, Gilgit-Baltistan, Pakistan, was acquired from Dudley Blauwet of Mountain Minerals International (Louisville, Colorado). The bodycolor of the inclusion suggested that it might be either of two equally rare pegmatitic phosphates, triplite or väyrynenite, that are known to occur in pegmatites in that part of the world (figure 2).

Figure 2. A combination of Raman and EDXRF analysis served to identify the inclusion as triplite. The inclusion is seen here using brightfield and fiberoptic illumination. Photomicrograph by Nathan Renfro; field of view 9.39 mm.

	Laser Raman microspectrometry was able to narrow the inclusion’s identity to these two suspected phosphates. Triplite and väyrynenite have very similar Raman peak patterns, and the topaz host masked some of the significant peaks needed to conclusively separate the two minerals. Since triplite contains iron and väyrynenite does not, focused energy-dispersive X-ray fluorescence (EDXRF) analysis was used to examine the inclusion’s chemical composition. Results indicated the presence of iron, identifying the inclusion as triplite. This marks the first time triplite has been reported as an inclusion in topaz. Source: GIA @topic:2


Title: Silvery Rutile “Tufts” in Quartz Abstract: Quartz crystals containing stellate tufts of silvery gray rutile were recently discovered in east-central California. Photomicrograph by Nathan Renfro; field of view 9.48 mm.

Recently, author JG discovered a deposit of rock crystal quartz in El Dorado County in east-central California. To date, more than 1,000 quartz crystals have been recovered from a single pocket in this deposit. Almost 50 percent of those crystals contained interesting silvery gray tufts of the titanium dioxide mineral rutile (see above), which was identified using Raman spectroscopy. Rutile in quartz typically occurs as golden needles, but it can occasionally be found as reddish brown, green, or silvery gray needles.

While the cause of the star-like needle arrangement in these particular clusters is not known, it is possible that the gray rutile is overgrown on a core crystal of anatase, which is a polymorph of rutile and might influence the morphology of the cluster. Tufts of golden rutile with a similar morphology have been observed overgrown on blue core crystals of anatase by author NR, which may explain the morphology in this sample; however, it was not possible to confirm this. A similar occurrence of gray rutile overgrowth is known to occur in the material sold as “platinum quartz” from Currelo in Minas Gerais, Brazil, where it is overgrown on the other rutile polymorph, brookite (see E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Vol. 2, Opinio Verlag, Basel, Switzerland, 2005, p. 588).

While production volume of quartz with these silvery rutile inclusions remains uncertain, this deposit has already provided interesting and beautiful additions to the micro-world. Source: GIA @topic:2


Title: Quarterly Crystal: Bubble in Fluorite Abstract: Figure 1. This 41.98 ct cluster of transparent green fluorite cubes contains a large primary two-phase fluid inclusion that was trapped between the cubes as they developed. Photo by Diego Sanchez.

The very lightly etched green fluorite crystals that come from the Rogerley mine, located in Rogerley Quarry, Weardale, County Durham, England, are well known for the beautiful bright fluorescence they display. Rogerley mine fluorite is highly fluorescent, turning bright bluish white on exposure to long-wave ultraviolet radiation.
The fluorescent fluorite from this locality will also take on a purplish color in sunlight. This effect, known as “daylight fluorescence,” appears to be unique to fluorite from the Weardale area. Research has shown that this intense fluorescence is due to an elevated rare-earth element (REE) content, including the elements cerium, lanthanum, neodymium, samarium, and yttrium.

Figure 2. In this registered pair of images, the movement of the gas phase in the fluorite cluster can be easily seen. Photomicrographs by Nathan Renfro; horizontal field of view 6.54 mm.
The Rogerley fluorite specimen shown in figure 1 measures 17.68 × 17.38 × 13.50 mm and weighs 41.98 ct. What makes this specimen the subject of this issue’s “Quarterly Crystal” is the presence of an eye-visible primary fluid inclusion with a moving gas phase. Along the interface, where the two growing crystals came together, negative space was created. This form of primary fluid inclusion hosts fluid remnants that were present when the fluorite was growing. When comparing the two photomicrographs in figure 2, the movement of the gas phase can be clearly seen. Fluid inclusions like this are not at all common in fluorite. Source: GIA @topic:2


Title: Mexican Opal with Large Fluid Inclusion Abstract: Figure 1. This 19.94 ct polished freeform opal contained a large, eye-visible three-phase fluid inclusion. Photo by Jian Xin (Jae) Liao; courtesy of Javier Lopez Ávila.

Although opals generally contain water in their structure, fluid inclusions large enough to be resolved with the microscope are rare; those that can be seen with the unaided eye are exceedingly rare. While at the JCK Show in Las Vegas, the author examined a most unusual common opal with a very large eye-visible fluid inclusion (figure 1). The fluid cavity was approximately 14 mm in diameter, and most of the space inside was occupied by a large gas bubble. An aqueous liquid could clearly be observed wetting the walls of the cavity, along with some unknown solid particles (figure 2). Since this fluid inclusion contained solid, liquid, and gaseous phases, it is appropriately described as a three-phase inclusion. According to Javier Lopez Ávila, the stone’s owner, this rare opal specimen was mined from the San Simon mine in Jalisco, Mexico, by Opalos de México. It is the first opal with a large fluid inclusion that he has observed from this deposit. This rare inclusion in Mexican opal is an interesting gemological oddity that any collector can appreciate.

Figure 2. This eye-visible three-phase fluid inclusion in a Mexican opal was just over 14 mm in diameter and contained solid, liquid, and gaseous phases. Photomicrograph by Nathan Renfro. Source: GIA @topic:12


Title: Dyed Serpentine Imitating Sugilite Abstract: Figure 1. These two beads, 6.96 ct (left) and 2.25 ct (right), were identified as dyed serpentine. Photo by Diego Sanchez.

The Carlsbad laboratory recently received a parcel of mottled purple beads (figure 1). A 2.25 ct translucent reddish purple broken bead from this parcel (shown on the right in figure 15) was examined for an identification report. At first glance, based on the color and structure, the sample resembled sugilite. Standard gemological testing revealed a refractive index of 1.56, a specific gravity of 2.71, weak orange fluorescence in both long-wave and short-wave UV, and a dye band with a handheld spectroscope. Sugilite has an RI of 1.607–1.610 and an SG of 2.74, and may show a concentrated band at 600 nm that can be confused with a dye band. The bead showed uneven color and a fibrous structure under the microscope (figure 2). There were no obvious dye concentrations, but the orange fluorescence and dye band in the spectroscope indicated the presence of dye. By performing a simple acetone test, we were able to prove that the material had been dyed. A light pink streak was examined after rubbing the test sample on a tissue soaked with acetone. The specimen’s infrared spectrum was not consistent with sugilite but ended up matching well with serpentine. Chemistry collected via laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) was consistent with serpentine, ruling out the possibility of sugilite.

Figure 2. The fibrous internal structure of the specimen resembling sugilite was actually consistent with serpentine. Photomicrograph by Jessa Rizzo; field of view 4.11 mm.
Without advanced testing, it would have been difficult to conclusively identify this material as serpentine. This is the first time reddish purple dyed serpentine imitating sugilite has been examined in the Carlsbad laboratory, and gemologists should be aware of this imitation when examining sugilite. Source: GIA @topic:12


Title: Quarterly Crystal: Orpiment in Barite Abstract: Figure 1. Numerous bright yellow crystals dominate the interior of this 74.31 ct barite cluster from Nevada. Photo by Nathan Renfro.

The 74.31 ct crystal cluster of transparent to translucent colorless barite columns shown in figure 1 measures 37.89 × 20.83 × 15.27 mm. It plays host to numerous small yellow crystals and radial sprays, which together give the cluster a light yellow color. The barite specimen is from the Regent mine in the Rawhide District of Mineral County, Nevada. The Regent mine was known to produce barite crystals with yellow orpiment inclusions in the mid-1990s. The pure yellow bodycolor of these numerous inclusions suggested they might be orpiment. Laser Raman microspectrometry was able to confirm our suspicions. Focused energy-dispersive X-ray fluorescence (EDXRF) analysis was used in an attempt to examine the chemical makeup of the inclusions, since orpiment contains arsenic as a main constituent. The EDXRF analysis showed the presence of arsenic. Based on chemistry, we determined that the yellow inclusions shown in figure 2 are indeed the arsenic sulfide mineral orpiment.

Figure 2. A combination of Raman and EDXRF analysis identified the inclusions as orpiment, a yellow arsenic sulfide. Photomicrograph by Nathan Renfro; field of view 3.83 mm. Source: GIA @topic:2


Title: Shrinkage “Footprint” in Rose Quartz Abstract: This 0.98 mm yellowish brown footprint-shaped epigenetic deposit of iron hydroxide was discovered in a pale pink rose quartz from Madagascar. Photomicrograph by Nathan Renfro; field of view 2.38 mm.

	Rose quartz is a widely distributed gem material. The specimen shown in was mined from pegmatites near the village of Tsaramanga, located in the Antananarivo province of Madagascar, and fashioned into a 34.11 ct rectangular step cut. It featured decorative epigenetic iron-colored debris that had been deposited in an extensive surface-reaching fracture. One of these debris patterns vividly calls to mind a dinosaur footprint left behind in soft mud.

	It appears that the fine particulate debris was suspended in water and subsequently deposited in the crack as a wet solution. As the water dried, the resulting shrinkage pattern formed as only the particles were left behind, a mechanism very similar to the formation of water spots when raindrops dry on a smooth glassy surface. So now “footprints” joins “fingerprints” in our inclusion lexicon. Source: GIA @topic:2


Title: Zircon Cluster in Ethiopian Sapphire Abstract: Figure 1. A very dense cluster of euhedral zircon associated with a larger rounded crystal of monazite, viewed under brightfield illumination. Photomicrograph by Charuwan Khowpong; field of view 1.75 mm.

Ethiopia is a known producer of opal, emerald, and commercial-grade sapphire. In March 2018, a GIA team collected a 1.911 ct blue sapphire from the Ch’ila mining area in the Tigray region. The inclusion scene shows a cluster of small transparent euhedral crystals with high relief. Raman spectroscopy identified the smaller crystals as zircon, but the clusters also contain some larger rounded monazite crystals (see above). Zircon is a common inclusion in blue sapphire, usually associated with metamorphic sources such as Myanmar, Sri Lanka, or Madagascar. Zircon inclusions from those deposits typically have more rounded shapes (E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Vol. 3, Opinio Publishers, Basel, Switzerland, 2008, pp. 188–308). The sapphire deposit in northern Ethiopia is related to alkali basalt, similar to the deposits in Australia, Nigeria, or Thailand. These sources rarely show clusters of euhedral zircon crystals. The presence of these zircon clusters might help to separate Ethiopian sapphire from other basalt-related sapphire sources. Source: GIA @topic:3


Title: A Horse-Shaped Inclusion in Pink Sapphire from Mozambique Abstract: The horse-shaped inclusion of phlogopite mica identified by Raman analysis. Photomicrograph by Charuwan Khowpong; field of view 2.40 mm.

Recently, GIA’s Bangkok lab received a 0.58 ct pink sapphire with a unique inclusion. Microscopic observation revealed needles, platelets, and particles, all of which are common inclusions found in Mozambican ruby and pink sapphire. The most interesting inclusion was found near the stone’s girdle. The crystal, which resembled a horse (see above), was identified as phlogopite. The most common mineral inclusions in Mozambican rubies are crystals of amphibole and mica (V. Pardieu et al., “Rubies from the Montepuez area (Mozambique),” 2013; V. Pardieu et al., “GIA lab reports on low-temperature heat treatment of Mozambique ruby,” 2015). Most of the mica inclusions are margarite or muscovite, typically with a lighter color and pseudohexagonal shape. Phlogopite is another end member of the mica series, but with a very different chemical composition from muscovite. To our knowledge, phlogopite mica has not been reported in Mozambican rubies or pink sapphires Source: GIA @topic:2


Title: Pink Tourmaline in Spodumene Abstract: Figure 1. Appearing as if suspended in water, a pink tourmaline inclusion in spodumene is illuminated by diffuse and fiber-optic illumination. Photomicrograph by Jonathan Muyal; field of view 7.19 mm.
The pegmatitic mineral spodumene commonly exhibits fluid inclusions as well as muscovite-mica, feldspar, and clay mineral inclusions (E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Vol. 1, ABC Edition, Zurich, 1986). A colorless 7.85 ct emerald-cut spodumene, purportedly from Afghanistan, was of particular interest for the eye-visible pink tourmaline crystal inclusion (figure 1) under the table facet. The mineral inclusion’s identity was confirmed by Raman microspectrometry analysis.

Although green tourmaline inclusions in spodumene have been documented (E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Vol. 3, Opinio Publishers, Basel, Switzerland, 2008, p. 642), very few references are found in the literature, and pink tourmaline in spodumene remains a rare occurrence. The transparent inclusion showed a well-formed trigonal prismatic crystal habit with fine vertical striations along its length (parallel to the c-axis). It exhibited a hemimorphic nature, with a flat termination on one end and a low pyramidal termination on the other. Abundant uneven wavy fractures, more or less perpendicular to the c-axis, were also visible within the crystal.
Of interest were some triangular etch marks common to spodumene. Although at first they appeared to be on the inclusion’s surface, they were actually on the spodumene interface. Additionally, the interface space exhibited vibrant iridescent colors when illuminated with oblique fiber-optic illumination (figure 2). This special guest inclusion thus gives the impression of having been “dressed and embellished” by its host spodumene and is displayed in its best attire.

Figure 2. Diffuse and fiber-optic illumination reveal the fine striations common to tourmaline along the length and the shallow triangular etch markings typical of spodumene along the interface, as well as vivid iridescent colors. Photomicrograph by Jonathan Muyal; field of view 1.26 mm.
Such a large tourmaline inclusion specimen in spodumene also provides valuable mineralogical information for the gemologist. The syngenetic inclusion and the host reflect their common pegmatitic geological genesis. The lithium-bearing granitic pegmatitic occurrence of spodumene strongly suggests that the inclusion is a lithia tourmaline variety, with lithium and aluminum substituting for iron and magnesium.

While spodumene is not known and prized for its inclusions, the beautifully highlighted pink tourmaline inclusion makes this gem a rare collector specimen. Source: GIA @topic:2


Title: Imitation Larimar Abstract: Pectolite is a mineral of the wollastonite group with the chemical formula NaCa2Si3O8(OH). It has a refractive index of 1.599–1.628, with a typical spot RI reading of about 1.60, and a specific gravity of 2.81. The light blue variety of this mineral, known by the trade name Larimar, has only been found in the Dominican Republic (R.E. Woodruff and E. Fritsch, “Blue pectolite from the Dominican Republic,” Winter 1989 G&G, pp. 216–225; see figure 1).

	Figure 1. This 3.91 ct ceramic imitation of Larimar (left) is shown with Larimar from the Dominican Republic. Photo by Lore Kiefert.
One of these contributors (PG) recently acquired a 3.91 ct drop-shaped cabochon, purchased in India as a Larimar imitation, that consisted of a ceramic material (figure 1, left). According to the vendor, the material was manufactured in China. Close microscopic examination showed white gas bubbles and blue color concentration (figure 2).

	Figure 2. Microscopic observation reveals dark blue color concentrations and whitish gas bubbles. Photomicrograph by Lore Kiefert; magnified 40x.
The cabochon’s spot RI reading of 1.53 and SG of 1.87 were distinctly lower than the values for Larimar. Semi-quantitative EDXRF chemical analysis gave a composition of 95% Al2O3 and 4% SiO2, with traces of SO3, K2O, CaO, Sc2O3, Cr2O3, Fe2O3, and Ga2O3. In contrast, the average composition of pectolite consists of 54.23% SiO2, 33.74% CaO, 9.32% Na2O, and 2.71% H2O.

Although the imitation material does indeed resemble Larimar, standard gemological tests such as microscopy, refractive index, and specific gravity should be sufficient to distinguish it.

Lore Kiefert
Gubelin Gem Lab Ltd.
Lucerne, Switzerland

Peter Groenenboom
AEL Arnhem
Arnhem, Netherlands Source: GIA @topic:2


Title: Une Découverte Exceptionnelle de Béryls Gemmes à Chaves, District de Vila Real, Portugal [An Exceptional Find of Gemmy Beryls at Chaves, District of Vila Real, Portugal] Abstract: The numerous pegmatites in Northern Portugal are known as sources of fine mineral specimens for mineral collectors. In this article, a passionate rockhound couple describes how, in 2011, after hard work and in constant bad weather, they hit upon a pocket with gemmy aquamarines and heliodors. The crystals measured 2.1–14.2 cm (0.8–5.7 inches). Their surfaces were slightly to moderately etched. Considering that there are relatively few gemstone occurrences in Western Europe, this find can be regarded as outstanding. The most beautiful crystals are shown in color photos.

Abstracted by Rolf Tatje Source: GIA @topic:1


Title: Trapiche Emerald from Swat Valley, Pakistan Abstract: Figure 1. Six emerald wafers reportedly from Swat Valley, Pakistan, showing a trapiche-like pattern. They range from 0.83 to 0.38 ct from left to right, with a thickness of about 1.51 to 2.08 mm. Photo by Kaiyin Deng.
Trapiche emeralds are usually found in Colombia. Recently the authors received six emeralds reportedly from Swat Valley, Pakistan, polished as double-sided wafers, retaining their original hexagonal crystal habit and exhibiting a trapiche-like pattern (figure 1). These samples weighed from 0.38 to 0.83 ct, with a refractive index of 1.588–1.599 and a birefringence of 0.009–0.011.

Figure 2. The trapiche emeralds from Pakistan were mainly composed of four parts: a green rim, a light green area, six arms, and a nearly colorless core as illustrated in figure A. These arms appear dark under transmitted light (B) and show bright metallic luster under reflected light (C); field of view 8.48 mm. Illustration and photos by Yujie Gao.
Generally, these trapiche emeralds were composed of four parts from rim to core: a green rim, a light green area, six arms, and a colorless core, as illustrated in figure 2A. The rims had a highly saturated green color, and most were relatively clean except for several fractures and tiny fluid inclusions. The rims ranged from approximately 1 to 2 mm wide. Although the boundary between the green rim and the light area was not very sharp, a hexagonal boundary was visible. Six black arms spread in a hexagonal symmetric pattern, with each arm perpendicular to the hexagonal side. The colorless core usually had a hexagonal shape.

Figure 3. Raman analysis identified these inclusions as magnetite. Peaks at 662 and 545 cm–1 agree with the two main peaks of magnetite, according to the RRUFF database, while peaks at 683 and 400 cm may be assigned to the emerald host.
Microscopic observation revealed that every arm contained many minute black platy inclusions. These small particles appeared dark under transmitted light (figure 2B), while they showed bright metallic luster under reflected light (figure 2C). Micro-Raman analyses (figure 3) identified these inclusions as magnetite. Peaks at 662 and 545 cm–1 were consistent with two main peaks of magnetite, according to the RRUFF online database (rruff.info), while peaks at 683 and 400 cm–1 may be assigned to the emerald host. Chemical analysis by energy-dispersive X-ray fluorescence (EDXRF) on the sample shown in figure 2 revealed an iron content of 20,860 ppm (n = 3) in the light green area and 17,000 ppm (n = 3) in the rim. The difference in iron content may be due to the inclusions, since magnetite (Fe3O4) is mainly composed of iron and oxygen.
To our knowledge, there have not been many reports of trapiche emerald from localities other than Colombia. The trapiche pattern caused by platy magnetite inclusions could help advance our understanding of trapiche. Source: GIA @topic:3


Title: Dendritic Inclusions in Nephrite from Dahua, China Abstract: Figure 1. The nephrite samples with dendritic inclusions from Dahua County. Photos by Zuowei Yin.
Since the 2010s, with the discovery of nephrite ore deposits in Luodian County, Guizhou Province, a significant amount of nephrite has been mined in the town of Yantan in Dahua Yao Autonomous County, located in the northwest of the Guangxi Zhuang Autonomous Region (Z. Yin et al., “Nephrite jade from Guangxi Province, China,” Fall 2014 G&G, pp. 228–235). Previously we reported on the nature of the chlorite inclusions found in this nephrite, and here we identify the chlorite as penninite.
The discovery of Dahua nephrite has eased the increasingly tight nephrite supply situation in China. Owing to its large reserves, the deposit has vast potential for future development. This material is of high quality and comes in a diverse array of colors including white, gray, light green, dark green, light yellow, and black. All bodycolors have been found to contain distinctive dendritic inclusions (figure 1). Dahua nephrite is popular with consumers, thus bringing huge economic benefit to the locality.
Dahua nephrite is mainly distributed around the river near the Yantan hydropower station. The ore body occurs in the limestone formed at the Qixian stage of the Paleozoic Permian system. The magmatic rocks in the area are basic intrusive rocks, divided into diabase and gabbro. The ore bed containing the nephrite is composed of dark gray stratified limestone of low to medium thickness, interspersed with fine calcite veins (B. Wang et al., “Gemmological and mineralogical characteristics of nephrite from Guangxi,” Journal of Gems and Gemmology, Vol. 14, No. 3, 2012, pp. 6–11). The samples were tested by standard gemological methods, polarizing microscopy, environmental scanning electron microscopy (ESEM), X-ray diffraction (XRD), Raman spectroscopy, laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS), and energy-dispersive spectroscopy (EDS). We conducted the tests at the National Key Lab of the China University of Geosciences in Wuhan.
The refractive index of Dahua nephrites ranged from 1.60 to 1.63. The average hydrostatic specific gravity was 2.99, and the Mohs hardness was about 6.5. These properties were very similar to those of the samples previously tested, which had a spot RI of 1.61–1.62 and a hydrostatic SG of 2.88–2.90 (Yin et al., 2014).
The Raman spectra (peaks at 225, 370, 676, 1029, and 3677 cm–1), infrared spectra, and X-ray powder diffraction (characteristic lines at 3.1189, 8.3968, 3.2702, and 2.7007 Å) were consistent with tremolite, showing that the main composition mineral of Dahua nephrite is tremolite with good crystallinity. Chemical composition analysis showed that the Mg2+/(Mg2+ + Fe2+) value of nephrite samples from Dahua was 0.973, identifying the main mineral as tremolite.
The REE distribution pattern of Dahua nephrite had an average value of ∑ REE and LREE/HREE of 5.32 and 2.60, respectively, indicating that Dahua nephrite is slightly enriched in light rare earth elements. The δCe of the samples ranged from 0.21 to 0.91, with an average value of 0.47, indicating a negative Ce anomaly. This suggests that Dahua nephrite was formed in a sedimentary metamorphic environment, with high oxygen fugacity and a single source of nephrite ore-forming fluid. The average δEu value of the samples was 0.71 in the range of 0.12–2.01, indicating a negative Eu anomaly. The negative Eu anomaly in this area may be due to the separation and crystallization during the ore-forming process of nephrite.
Most nephrite in Dahua has dendritic inclusions whose colors are mainly brownish yellow, brownish green, and black distributed in the form of branches, clumps, and the like. These “variegated” inclusions were actually determined to be penninite (belongs to the chlorite group) using modern techniques including routine gemstone testing, X-ray powder diffraction, scanning electron microscope, and EDS. According to the composition determined by EDS testing, we calculated the atomicity of Si with O20 as a reference. The results were as follows: The number of Si atoms was 6.4, and Fe2+/Fe + Mg was 0.16, indicating that the chlorite inclusion was a type of penninite (red cross in figure 2, from the chlorite classification scheme in Y. Hu et al., “Related studies on characteristic altered mineral chlorite,” West-China Exploration Engineering, No. 11, 2019, pp. 132–134).

Figure 2. EDS compositional analysis showed that the chlorite inclusion in Dahua nephrite was penninite. From the chlorite classification system in Hu et al. (2019).
The variegated chlorite inclusions in Dahua nephrite are very useful identifying characteristics. With the exception of Luodian nephrite, which contains similar inclusions, such distinctive dendritic inclusions have yet to be discovered in white nephrite deposits; therefore, it is potentially a significant tracer for origin. The Dahua nephrite contains penninite, a type of chlorite (i.e., hydrothermally metamorphosed tremolite) (Yin et al., 2014). As an inclusion unique to Dahua nephrite, penninite serves as an important reference for origin tracing. Source: GIA @topic:13


Title: Durability Testing of Filled Emeralds Abstract: Researchers treated 128 emeralds with nine emerald fillers—Araldite 6010, cedarwood oil, paraffin oil, unhardened and surface-hardened Opticon, a mixture of cedarwood oil and Canada balsam, surface-hardened Norland Optical Adhesive 65, and the solid fillers Gematrat and Permasafe—and then exposed them (along with 14 unfilled emeralds) to common conditions of wear and cleaning. All emeralds were held for about six years, and most were then subjected to one of the following durability tests: exposure to long-wave UV radiation (a component of sunlight), to mild heat and incandescent light in a display case, to five chill-thaw cycles, and to a desiccation environment; ultrasonic cleaning with either warm water or BCR; and cleaning with steam or mild chemical solvents. Changes were evident in about 35% of the filled emeralds after the mild exposure tests (i.e., time, UV radiation, display case); those with liquid fillers were especially susceptible. The desiccation environment made fissures visible in a majority of emeralds. Hard fillers damaged their host emeralds by expanding cracks during durability testing, while chill-thaw cycling extended cracks in both filled and unfilled emeralds. Emeralds with liquid fillers were most susceptible to appearance changes due to ultrasonic cleaning and exposure to ethanol or acetone. Some observations on the effectiveness of different fillers on emerald appearance are also provided. Source: GIA @topic:3


Title: The Yellow Color Center and Trapped Electrons in Beryl Abstract: Investigations continue into the cause of yellow color in beryl. The generally accepted explanation is that it is related to the charge-transfer between Fe3+ ions substituting for octahedral Al3+ ions in the crystal and the surrounding oxygen ions.

							Using electron paramagnetic resonance (EPR), an absorption technique that uses magnetic fields to measure transition energies in atomic defect centers, this study contradicts the accepted interpretation, proposing an alternate model.

							Although a strong EPR signal from octahedral Fe3+ ions can be found in beryl of all colors, including colorless, the study determined that Fe3+ ions substituting for Al3+ at the octahedral position cannot be the cause of the yellow color. There is, however, a signal unique to yellow beryl that comes from Fe3+ ions at a tetrahedral site.

							The author proposes a simple model describing the oxidation and reduction processes involving iron electrons trapped in the crystal structure to explain the creation and decay of the yellow color. This study discusses reinterpretations of other experimental findings that lead to different explanations for beryl’s colors.

Abstracted by Edward R. Blomgren Source: GIA @topic:3


Title: Determining the Geographical Origins of Natural Emeralds Through Nondestructive Chemical Fingerprinting Abstract: The technology to identify a gemstone’s geologic and geographic origins has improved in the last decade to the point where accurately pinpointing the locality has become a reality. Using emeralds from different mines in the Cordillera Oriental region of Colombia, some of them only a few miles apart, scientists can now discern minute differences in chemical composition and determine each sample’s point of origin by studying the chemical “fingerprints” in their chromophores. The chromophores are trace elements of vanadium, nickel, or magnesium and vary geographically as a result of interstitial fluid migration prior to precipitation.

						After recognizing that within-site chemical homogeneity and cross-site chemical heterogeneity depended on the amount of chromophores in the crystal structure, the authors sought to find out if chemical heterogeneity between emerald mining localities was chemically unique and statistically provable based on chromophore components alone. Included in the study were emerald samples from the Muzo, Cosquez, and Guali mines of Colombia, plus the Campo Verdes and Carnaíba mines in Brazil, and the Chantete mine in Zambia. Consideration for sample inclusion in this study involved the history of the host rock chemistry on the skeletal crystal structure, the occurrence of trace elements that link emeralds to their point of origin, the subsurface geology, fluid-rock interactions and the geochemical processes leading to emerald formation.

						The study concluded that element-based heterogeneity exists between the six emerald mining sites. Through the use of an Amray scanning electron microscope (SEM) coupled to an EDAX energy-dispersive X-ray spectrometer (EDX), statistically significant chemical heterogeneity between mine sites was revealed by a non-destructive test that preserved the integrity of the sample.

Abstracted by James E. Shigley Source: GIA @topic:1


Title: Wittichenite from the Cattle Grid Pit, Mount Gunson Mine, South Australia Abstract: In 1981, large, attractive wittichenite crystals found at the Cattle Grid Pit in South Australia were mistaken for chalcocite. Then in 2008, they were correctly identified by the Smithsonian Institution. Electron microprobe analysis of this species shows Cu, Bi, and S (weight percentages of 38.67%, 41.70%, and 19.90%, respectively).

					The Cattle Grid wittichenite is brittle, with strongly conchoidal fractures and a relatively low hardness. The colors vary from highly lustrous silvery white to bronze to a deep purple-black. The crystals are predominantly tabular-prismatic in habit, but some show myriad crystal faces and deeply striated prisms. The Miller indices for these crystal forms, and their intricate and complicated crystal morphology, are discussed in depth.

					The article contains 16 large photos of wittichenite, some crystals weighing more than 75 grams, as well as the mine site and the copper localization stratigraphy. The number of wittichenite crystals larger than 2 cm in maximum dimension is estimated to be about 30, and these are held in only three collections (two institutional and one private). Unfortunately, the entire production of copper sulfide concentrate from the Cattle Grid Pit is now owned by a private smelter, where the bismuth-containing wittichenite is considered an undesirable impurity.

Abstracted by Edward R. Blomgren Source: GIA @topic:2


Title: Yellow, Green, and Blue Sapphires Reportedly from Antang and Gombe, Nigeria Abstract: Figure 1. These sapphires (0.64–8.27 ct) are from Antang and Gombe, in northern Nigeria. Photo by Shunsuke Nagai.
GIA’s Tokyo laboratory borrowed 19 sapphires (figure 1) from gem dealer Ambrose & Co. in Kofu, Japan. The samples consisted of eight blue, one bluish green, eight yellow, and one greenish yellow/blue bicolor sapphires, all faceted. They were reportedly from Antang and Gombe in northern Nigeria (figure 2). Mambilla, in the southeastern part of the country, is the only well-known Nigerian sapphire source (V. Pardieu et al., “New Nigerian source of blue sapphire,” 2014, https://www.gia.edu/doc/Nigeria_Mambilla_Sapphire_US.pdf; Spring 2017 GNI, pp. 134–135), and the two new sources are not well documented.

Figure 2. Map of Nigerian sapphire sources. Sapphires from the new deposits at
Antang and Gombe have potentially high quality.
Sapphires from both Antang and Gombe are basalt related. The mines are located in a basement complex and on Cretaceous/Tertiary sedimentary rocks near volcanic rocks. The sapphires are mined in alluvial deposits or unconsolidated sediments. According to the dealer, the blue sapphires were from Antang and the yellow sapphires and bicolor sapphire from Gombe. Brume Jeroh, the supplier in Nigeria, mentioned that Antang produces blue, green, yellow, and parti-color sapphires, while Gombe produces mainly yellow sapphires and a few blues. He also noted that stones from these sources may have been mixed together at the market in the city of Jos.

The samples’ standard gemological properties are listed in table 1. Refractive index and specific gravity values were all within the range of corundum. Representative inclusions observed in these sapphires are shown in figures 3 and 4. Quantitative analysis of trace elements was carried out with LA-ICP-MS, and the results are summarized in table 2 and figure 5.

TABLE 1. Standard gemological properties of sapphires from northeastern Nigeria.

Samples
Color
Weight (ct)
Refractive index
Specific gravity
Source

N01
Yellow
2.84
1.763–1.770
4.00
Gombe

N02
Yellow
2.07
1.765–1.773
4.02
Gombe

N03
Yellow
2.06
1.764–1.772
4.00
Gombe

N04
Yellow
1.84
1.764–1.771
4.00
Gombe

N05
Yellow
1.28
1.764–1.772
4.01
Gombe

N06
Yellow
1.21
1.767–1.772
3.99
Gombe

N07
Yellow
1.03
1.762–1.770
4.00
Gombe

N08
Yellow
0.94
1.762–1.770
4.00
Gombe

N09
Yellow
0.78
1.762–1.770
3.99
Gombe

N010
Greenish yellow and blue
2.04
1.762–1.770
4.03
Gombe

N011
Bluish green
3.51
1.764–1.772
4.01
Gombe*

N012
Blue
2.09
1.763–1.772
4.00
Gombe*

N013
Blue
8.27
1.760–1.768
3.99
Antang

N014
Blue
2.15
1.762–1.770
4.00
Antang

N015
Blue
1.82
1.762–1.770
4.00
Antang

N016
Blue
1.16
1.762–1.770
4.00
Antang

N017
Blue
0.97
1.765–1.770
3.99
Antang

N018
Blue
0.88
1.764–1.771
3.99
Antang

N019
Blue
0.64
1.760–1.768
3.98
Antang

*Samples N11 and N12 were supplied as Antang sapphires but could be Gombe sapphires that were mixed at the market in Jos. This study identified their origin as Gombe based on LA-ICP-MS results.

Figure 3. Inclusions in sapphires from Gombe: healed fissures with hazy edges (A), irregular particles and short needles (B), wavy graining (C), and flake-like particles (D). Photomicrographs in darkfield illumination (A–C) and diffused brightfield illumination (D) by Shunsuke Nagai. Fields of view 1.95 mm (A), 2.15 mm (B), 2.80 mm (C), and 2.80 mm (D).

Figure 4. Inclusions in sapphires from Antang: zircon crystals (A), reflective thin films with hexagonal patterns (B), bands of minute particles and short needles (C), and angular banding and perpendicularly oriented particles (D). Photomicrographs in darkfield illumination by Yusuke Katsurada (A–C) and Shunsuke Nagai (D). Fields of view 2.80 mm (A), 1.00 mm (B), 4.00 mm (C), and 4.30 mm (D).

Figure 5. LA-ICP-MS quantitative analysis allowed the separation of blue sapphires from Antang and yellow sapphires in some trace elements (e.g., Fe vs. V and Fe vs. Ga). The two parts (N10Y and N10B) of the bicolor sapphire show a close trend. The bluish green sapphire (N11) and blue sapphire (N12) are considered to be from Gombe. Results are not averaged.

TABLE 2. Trace element concentrations (in ppma) obtained by LA-ICP-MSa.

Sample no.
Be
Mg
Ti
V
Cr
Mn
Fe
Ga

N01
0.38
11.4
10.9
1.65
bdl
0.18
2610
68.9

N02
bdl
14.2
12.6
2.0
0.28
0.21
2790
60.9

N03
bdl
15.8
12.1
0.47
bdl
0.08
2970
36.7

N04
bdl
22.8
21.4
1.51
2.36
0.25
3860
39.0

N05
bdl
16.0
13.3
1.88
1.05
0.03
2660
71.6

N06
0.45
20.2
17.6
2.27
3.36
0.04
2667
66.1

N07
bdl
14.9
12.4
1.69
bdl
0.13
2900
70.7

N08
bdl
12.3
33.8
1.04
bdl
bdl
1930
89.9

N09
bdl
16.2
14.2
1.82
0.61
0.11
2760
71.0

N010Y
bdl
15.4
13.7
1.66
bdl
0.10
2740
68.0

N10B
bdl
8.98
40.2
1.67
bdl
0.03
2490
66.6

N011
bdl
10.8
14.6
2.04
21.9
0.27
4000
67.9

N012
1.19
6.88
17.5
1.80
bdl
bdl
2380
78.9

N013
bdl
2.25
21.2
4.79
20.9
0.06
807
45.6

N014
bdl
12.8
21.4
6.82
0.37
0.06
1290
49.7

N015
bdl
7.37
92.0
8.79
3.27
bdl
924
56.4

N016
bdl
13.4
60.6
7.22
bdl
0.11
1280
61.0

N017
bdl
8.16
18.4
5.20
5.03
0.03
1470
54.1

N018
bdl
5.10
30.0
6.47
18.3
bdl
1190
49.7

N019
bdl
4.27
30.1
5.89
4.81
bdl
1260
52.7

aAverage of three spots
			bdl: below detection limit

The yellow sapphires and the greenish yellow part of the bicolor sapphire showed a typically high Fe, and their Mg concentration is greater than Ti except for one sample (N08; again, see table 2). As shown in figure 5, the high Fe (approximately 2000 ppma) and medium V (approximately 0.50–2.00 ppma) of all the yellow sapphires (N01 to N09) and the greenish yellow part of the bicolor sapphire (N10Y) showed the same trend as those of a bluish green sapphire (N11) and one blue sapphire (N12). The greenish yellow part of the bicolor sapphire (N10Y) matches other yellow sapphires in all elements, and the blue part of the bicolor (N10B) overlaps with N11 and N12. The titanium levels are significantly different between the two parts of N10. This matters, as the titanium is necessary for blue coloration in sapphire with iron. N11 and N12 show different trends from other blue sapphires (from N13 to N19) for V, Fe, and Ga. This suggests that these two samples originated from a different locality. Given that these two samples’ trace element composition is close to that of the blue part of the bicolor sapphire (N10B) and different from the rest of the blue sapphires, we considered them to be from Gombe (again, see table 1). In addition, inclusions exhibited in figure 4 in N13–N19 were not seen in N11 and N12, and these two samples had similar features to each other, as shown in figure 3. Greenish blue and blue sapphires (N11 and N12) and the blue part of the bicolor sapphire (N10B) from Gombe show high Fe (approximately 2000 ppma) and medium V (approximately 1.50–2.00 ppma). Blue sapphires from Antang (from N13 to N19) show lower Fe (approximately 800–1500 ppma) and high V (approximately 4.50 ppma).

Although sapphires from these two new Nigerian sources are limited in quantity and color range, they are potentially high quality. The importance of the sources is not yet known, and more field data and advanced testing data such as quantitative analyses of trace elements are needed. Despite the different trends in some trace elements between the localities, as this study revealed, they still overlap with trace elements of different magmatic origins including Mambilla (data not shown). Since characteristic inclusions are not always present in basalt-related sapphires and trace elements cannot always be separated, origin determination of these sapphires remains challenging. Interpretation of trace element data such as discriminant analyses and the building of a rich database are necessary. Source: GIA @topic:3


Title: Hydrophane Opal Treatment Abstract: Figure 1. Top: These five opal slices of comparable thickness were cut from the same rough. They were semitransparent to translucent when viewed in daylight on a black background. Play-of-color was displayed with oblique lighting at certain angles. Bottom: The slices’ transparency improved after immersion in distilled water for approximately 20–30 minutes. Each slice absorbed water differently depending on its porosity. Photos by Nuttapol Kitdee.

Recently in GIA’s Bangkok lab, an approximately 4 cm piece of rough hydrophane opal was fabricated into five slices for various treatment experiments. Each slice was approximately 0.5 cm thick. Only clean tap water was used in the cutting process, and no other materials besides opal were involved. The opal slices showed a whitish, cloudy appearance in daylight and appeared light brown to brown in calibrated diffused light.

After the cutting step, all five slices underwent specific gravity testing, which gave SG values of approximately 1.93 ±0.03. While immersed in water, the slices displayed obvious weight gain and improved transparency, which indicated that the material was hydrophane opal (figure 1).

The water-absorbing ability of the opal was found to vary through the whole piece, resulting from its non-uniform porosity, and could be calculated as percentage weight changes in water, ranging from 5% to 13%. It took approximately one week to restore the opal’s original weight and appearance.

Two slices were then selected for oil and Opticon treatment experiments. The treatment procedures were identical. The pieces of opal were heated to approximately 80°C and then placed in warm oil or Opticon of the same temperature under vacuum conditions. They were heated continuously for 15 to 20 minutes, which was indicated by the presence of gas bubbles on the opal. Once the slices had fully absorbed the oil or Opticon, there were few, if any, gas bubbles. Afterward, the slices were removed, cleaned with a dry cloth, and left to air-dry overnight at room temperature.

Both treated opal slices were analyzed using a gemological microscope and advanced instruments. Oil treatment improved transparency but destroyed play-of-color (table 1, left). Opticon treatment enhanced transparency while preserving play-of-color (table 1, right). The FTIR spectrum of the oil-treated slice showed oil-related peaks at 5670, 5789, and 5860 cm–1, whereas the FTIR spectrum of the Opticon-treated slice displayed a series of related peaks in the 5600–5900 cm–1 range (figure 2). Raman spectra also demonstrated the presence of treatments. The oil-treated sample displayed peaks at 2929, 2897, 2873, 2851, and 2724 cm–1, while the Opticon-treated slice showed dominant peaks at 3071, 2931, and 2873 cm–1, and a series of smaller peaks in the 600–1600 cm–1 range (figure 3).

Figure 2. FTIR spectra of untreated, oil-treated, and Opticon-treated opal. The two treated
opals show characteristic FTIR peaks in the 5600–5900 cm–1 range, while untreated opal
does not show any peaks in this range.

Figure 3. Raman spectra of untreated, oil-treated, and Opticon-treated opal. The oil-treated
opal shows characteristic Raman peaks at 2929, 2897, 2873, 2851, and 2724 cm–1. The
Opticon-treated opal displays characteristic Raman peaks at 3071, 2931, and 2873 cm–1,
with a series of smaller peaks in the 600–1600 cm–1 range.
While oil and Opticon are not easily observed with the unaided eye or even with a microscope, they are readily detected by advanced instruments. Using Opticon, the process could be combined with other treatments, such as dyeing or sugar-acid treatment, to improve the durability and transparency of opal.

Acknowledgement: The authors thank Jeffery Bergman of Primagem, Bangkok for providing and performing treatment on the Ethiopian hydrophane opal samples examined in this Lab Note. Source: GIA @topic:12


Title: Books: Collector’s Guide to the Zeolite Group Abstract: By Robert J. Lauf, softcover, 112 pp., publ. by Schiffer Books, Atglen, Pennsylvania, 2014, $19.99.

Collector’s Guide to the Zeolite Group is the 17th volume in the Schiffer Earth Science Monograph Series, and the 14th authored by Robert Lauf. Some of Lauf’s previous publications, including his work on beryl, garnet, and quartz, are of immediate interest to gemologists, while others, such as this book, may appeal more to mineralogists and geologists. Zeolites are a fascinating group of rock-forming minerals that are beloved by collectors, as they can form exceptional crystals and aggregates. Often lacking durability or distinctive beauty, they rarely appear as finished gemstones. As a working gemologist, I have only encountered a few zeolite minerals in the course of my education and everyday work: natrolite (as radial aggregates and a component of maw-sit-sit), pollucite, and thomsonite (fibrous aggregate).

Zeolites are structurally complex and are distinguished by their ability to exchange cations with surrounding solutions. They are immensely important for industrial purposes as sorbents, catalysts, and molecular sieves. While these minerals occur naturally, they are also produced as “designer” synthetics on a large scale. Over 200 “frameworks” of open cavities and channels formed by tetrahedral oxygen atoms surrounded by cations have been identified; of those, over 40 are natural occurrences. Zeolites are used in agriculture (animal feed, odor control, pet litter), horticulture (soil conditioners and growth media), and water purification. They are also act as carriers for pesticides and fungicides, and as gas and oil absorbents.

The introduction briefly discusses the research and literature on zeolites, citing a few detailed examples of use. Through cation change, naturally occurring cliniptolite can be used to filter radioactive cesium from wastewater at nuclear power plants.  Zeolites can be used as “molecular sieves” to separate molecules with differing cross sections (i.e. branched and unbranched hydrocarbons) in a vapor stream. The structure and morphology section tries to clearly lay out the structural chemistry and taxonomy of the group, but the book quickly goes beyond the scope of knowledge, comprehension, and expertise of the average gemologist or collector. The structural types are illustrated with diagrams that enhance the understanding of the unique framework structure and the functional “channels” and “cages.” The following chapter outlines zeolite’s formation and geochemistry, pointing out the environments where specimen-quality rough may be sourced, versus massive industrial-quality deposits.

The strength of the book is the alphabetized section on each type of zeolite, illustrated with superbly formed examples. The photography is also breathtakingly artistic. If the fascinating structure and utility of zeolites does not intrigue a budding collector, the pure aesthetics of the specimens surely will. Each entry describes locality information and associated minerals; a few include additional diagrams to illustrate the framework structure and different examples of crystal morphology.

The book concludes with a comprehensive and somewhat overwhelming list of references, but the reader is guided by the author’s annotations. Lauf also highlights a few resources of notable interest to those starting their own collection.

Like other books in the Earth Science Monograph Series, this volume is not a valuation guide, nor does it give an indication of the commonness or rarity of particular types of specimens. It serves as an excellent primer to the unique structure and function of this unique mineral group. In addition, the abundant high-quality illustrations of superb specimens will make this volume appealing even to an “armchair” mineral collector. Source: GIA @topic:1


Title: Quarterly Crystal:Mystery in Topaz Abstract: Figure 1. The interior of this 5.10 ct Sri Lankan topaz is dominated by a dramatic inclusion scene. Photo by Kevin Schumacher.

Occasionally we run into an inclusion identification problem we just can’t solve. Such was the case with the 5.10 ct topaz from Elahera, Sri Lanka, shown in figure 1. This transparent colorless crystal, acquired from Kusum S. Naotunne (Colombo, Sri Lanka), hosts a prominent translucent light green crystal and a flowery cluster of hexagonal opaque silvery black plates (figure 2). The bodycolor and characteristic form of the green inclusion suggest fluorite; this was confirmed by laser Raman micro-spectrometry.

Figure 2. While the light green crystal was identified as fluorite by Raman analysis, the
opaque platy inclusions were too deep to be identified. Photomicrograph by Nathan
Renfro; field of view 5.87 mm.
Analysis of the opaque black plates was a more difficult matter. GIA’s Carlsbad lab staff employed Raman to identify the plates, but the inclusion was too deep to get any signal other than the spectral lines of the topaz host. Energy-dispersive X-ray fluorescence (EDXRF) was attempted to pick up any hints of the plates’ chemical composition, but useful information continued to elude such efforts. It became clear that destructive analysis would be needed to clearly identify the black plates. Since this was an inclusion combination, we decided that this topaz should be preserved unaltered for future exploration. Surely one day technological advances will allow the identification of this mystery inclusion, but for now it is enough to enjoy the aesthetics of such a beautiful included crystal and the fascinating exploration of its inner world. Source: GIA @topic:2


Title: Rock Crystal with Cross Inclusion Exhibiting Brownian Motion Abstract: Figure 1. A rock crystal pendant measuring 48.5 × 31.2 × 8.8 mm with a white cross inclusion. Photo by Tsung-Ying Yang.

Figure 2. The white cross inclusion in the rock crystal contained this two-phase inclusion, in which the bubble had a diameter of approximately 2 μm and exhibited Brownian motion. Photo by Shu-Hong Lin; field of view 65 μm.
Recently, the authors encountered a transparent faint yellow pendant with a striking white cross inclusion (figure 1). Raman and Fourier-transform infrared spectroscopy identified the pendant as rock crystal. Microscopic observation revealed that the white cross was composed of numerous two-phase inclusions measuring less than 20 μm. One of the two-phase inclusions contained a gas bubble with a diameter of approximately 2 μm (figure 2) that was found to exhibit Brownian motion due to the influence of water molecules (see video below). Brownian motion refers to the unstable random movement of microscopic particles in a fluid, caused by continuous bombardment from molecules of the surrounding medium. This motion becomes more pronounced as the particle size decreases, fluid viscosity lowers, and temperature increases. Brightfield illumination, polarized light, and optical zoom techniques were used to obtain the photomicrographs.

	Two-Phase Inclusion Exhibits Brownian Motion Source: GIA @topic:2


Title: Thin-Film Fluid Inclusions in Aquamarine Abstract: Thin-film fluid inclusions oriented perpendicular to the c-axis of this aquamarine display interference colors when viewed using oblique fiber-optic illumination. Photomicrograph by Muzdareefah Thudsanapbunya; field of view 2.79 mm.

The author recently examined a faceted aquamarine from Brazil that showed two-phase (liquid and gas) thin-film inclusions of different sizes and shapes. When observed using oblique fiber-optic illumination, the inclusions revealed a kaleidoscopic play of interference colors (see above). The most diagnostic beryl inclusions, yet barely noticeable in brightfield illumination are ultra-thin-film fluid inclusions. The planar surface of these inclusions is oriented parallel to the basal pinacoid of their host (E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Volume 2, Opinio Publishers, Basel, Switzerland, 2005, pp. 312–314). The presence of the bright iridescent thin-film fluid inclusions resembles colorful rainbow sprinkles. Source: GIA @topic:3


Title: Apatite in Hackmanite Abstract: Figure 1. A hackmanite with a faded purple color after storage in the dark (left), illuminated with long-wave UV light (center), and after removal from a few seconds of exposure to the long-wave UV light (right). The color has deepened after exposure to UV light. Photos by Ronnakorn Manorotkul.
Hackmanite, Na8Al6Si6O24(Cl2,S), is a variety of sodalite notable for its tenebrescence. When kept in darkness, samples can fade to pale purple and even gray or translucent to opaque white. When exposed to long-wave ultraviolet illumination, they can display a strong orange fluorescence reaction. After exposure to sunlight or artificial light with a UV component, samples can quickly develop a much stronger color. One hackmanite sample recently examined by the author (figure 1) showed this phenomenon.

Figure 2. Left: In darkfield illumination, a white apatite crystal is visible in the hackmanite. Right: After exposure to long-wave UV light for approximately one second, a dramatic change can be seen. The overall color of the hackmanite is now a more vivid shade of purple. Photomicrographs by E. Billie Hughes; field of view approximately 5 mm.
Another hackmanite was submitted that displayed an interesting elongated white inclusion (figure 2, left) that was identified by micro-Raman as apatite. As we examined the sample in the microscope, we tried exposing it to a 6-watt long-wave UV light for approximately one second. Almost immediately, a change was observed. The hackmanite developed a more vibrant purple color that is clearly displayed in figure 2 (right). Source: GIA @topic:2


Title: Synthetic Sapphire and Synthetic Spinel Doublets Abstract: Figure 1. These two doublets, a 6.45 ct greenish yellow oval mixed cut and a 4.17 ct greenish yellow cushion mixed cut, contained a synthetic spinel crown and a synthetic sapphire pavilion. Photo by Robison McMurtry.

	Assemblages have been used to imitate various gemstones for many years. Some of the most common are garnet and glass doublets, sapphire and synthetic corundum doublets, synthetic spinel triplets, and beryl triplets.

	The Carlsbad laboratory recently examined two uncommon doublets: a 6.45 ct greenish yellow oval mixed cut and a 4.17 ct greenish yellow cushion mixed cut (figure 1). Initial microscopic observation revealed a separation plane near both girdles with flattened, trapped gas bubbles in colorless cement (figure 2, center). The green crowns were joined to the yellow pavilions with this colorless cement (figure 2, left). An RI of 1.728 and whitish chalky fluorescence under short-wave UV on both crowns were suggestive of synthetic spinel. One of the doublets showed thick green curved color banding. Photoluminescence (PL) emission spectra identified the crowns as synthetic spinel.

	Figure 2. Left: The green crown and yellow pavilions of the 6.45 ct oval mixed cut are easily observed in immersion. Center: A separation plane near the girdle with a flattened, trapped gas bubble; field of view 1.76 mm. Right: Parallel twining planes in the pavilion; field of view 2.90 mm. Photomicrographs by Nathan Renfro.

	In both doublets, the pavilion had a refractive index of 1.760 to 1.768 and was inert to UV radiation. The two assemblages were clean and showed only twining planes (figure 2, right). Faint yellow curved color banding was visible when they were immersed in methylene iodide and observed with a blue color filter. EDXRF analysis showed a chemical composition consistent with synthetic corundum. They contained Ni as a trace element and no Fe, Ga, or Ti.

	Microscopic observation and advanced gemological testing confirmed that these were doublets consisting of a synthetic spinel crown and a synthetic sapphire pavilion, joined together with a colorless cement. These are the first assemblages of synthetic spinel and synthetic sapphire observed by GIA. Source: GIA @topic:3


Title: Unusual Composite Apatite-CO2 Inclusions in Sapphires from Ohn Bin Yee Htwet, Myanmar Abstract: Figure 1. Composite apatite/CO2 inclusion in a sapphire from Ohn Bin Yee Htwet. Photomicrograph by Aaron Palke; field of view 1.99 mm.

Routine investigation of a parcel of sapphires from Ohn Bin Yee Htwet near Mogok in Myanmar revealed something unexpected. Unusual composite inclusions were observed where one part of the inclusion exhibited flat, crisp, angular planes, while the other part showed an irregular and rough surface (figure 1). Raman spectroscopy identified the two phases as apatite (the flat, crystalline-looking area) and CO2 (the rough and irregular surface).

Figure 2. A myriad of inclusions at the boundary between the dense, silky core and the unincluded rim. Photomicrograph by Jonathan Muyal; field of view 1.76 mm.
The rough and irregular part of the inclusion also showed a gas bubble within the fluid CO2, which disappeared when warmed in the well light of the microscope as the gas and liquid homogenized. These inclusions generally sit atop a dense nest of rutile silk. The rutile silk is tightly clustered in the core of the sapphire crystals and terminates rather abruptly. A myriad of inclusions is often found at the boundary between the dense, silky core and the unincluded rim (figure 2).
While both apatite and CO2 are routinely observed in sapphires from a variety of sources, finding both phases in a single inclusion is unexpected and has not been previously reported, to the author’s knowledge. It is hypothesized that these inclusions formed when apatite was trapped within the sapphire and created a growth blockage, thus allowing the fluid present (CO2) to adhere to the surface of the apatite and sapphire to become included as well. Source: GIA @topic:3


Title: Natural Black Coral with Polyp Structure Abstract: Figure 1. The surface of the black oval cabochon displayed a vivid example of the diagnostic polyp structure in black coral, shown using reflected light. Photomicrograph by Britni LeCroy; field of view 2.90 mm.

The authors recently examined a large black oval cabochon that was opaque with a slight waxy luster. Microscopic examination revealed a layered concentric tree-like structure when a fiber-optic light was used, as well as round ring-like spherical structures. These observations are consistent with coral, and these individual spheres are referred to as polyps (figure 1).

Figure 2. Using oblique fiber-optic illumination, the orangy brown color and polyp structure were clearly visible. Photomicrograph by Britni LeCroy; field of view 2.90 mm.
This is a great example of the diagnostic surface structure produced when black coral is cut and polished into a cabochon. Oblique fiber-optic lighting revealed an intense orangy brown and black pattern, also consistent with the polyp structure of natural black coral (figure 2). This was the clearest example of this polyp structure the authors have examined in black coral. For additional information and images on black coral, see E.W.T. Cooper et al., Guide to the Identification of Precious and Semi-precious Corals: In Commercial Trade, World Wildlife Fund, Vancouver, Canada, 2011. Source: GIA @topic:5


Title: Parisite Crystals in a Colombian Emerald Abstract: Parisite crystals in an emerald from Colombia, shown under oblique fiber-optic illumination. Photomicrograph by Kyaw Thu; field of view 0.125 mm.

The author recently examined a 1.21 ct transparent faceted emerald. Gemological observation and chemical and spectroscopic analysis indicated that this natural emerald originated from Colombia. Moreover, microscopic examination with a combination of oblique fiber-optic and darkfield illumination presented the classic jigsaw pattern with a three-phase inclusion; this type of primary fluid inclusion is relatively common in Colombian emeralds. Interestingly, oblique fiber-optic illumination detected some colorless transparent crystal inclusions surrounded by fluid, as seen in the above figure.
Raman microspectrometry analysis of the well-formed prismatic crystals indicated that the unusual fluorocarbonate minerals were parisite. These very rare parisite mineral inclusions have been found only in emeralds from the Muzo mine (Winter 1982 Lab Notes, p. 230; E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Vols. 1–3). Source: GIA @topic:2


Title: Garnet in Sapphire Abstract: This sapphire contains a beautiful garnet inclusion and a trail of dust-like rutile particles. Photomicrograph by Michaela Stephan; field of view 4.79 mm.

The author recently examined a 3.26 ct sapphire that changed from green-blue in fluorescent light to reddish purple in incandescent light. The color-change sapphire contained a large eye-visible crystal inclusion (see above). Microscopic examination of the singly refractive inclusion revealed garnet’s characteristic dodecahedral crystal shape with rounded edges.
Of all the possible inclusions contained within sapphire, garnet is a rare and beautiful occurrence. When garnet crystal inclusions do occur, they often indicate an origin of Tanzania or the U.S. state of Montana (E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Vol. 3, Opinio-Verlag Publishers, Basel, Switzerland, 2008, pp. 228–242). In this sapphire, a large vibrant orange garnet is followed by a trail of dust-like rutile particles, much like an asteroid streaking across the night sky. Source: GIA @topic:3


Title: Amber with Insect-Bearing Filling Abstract: Figure 1. The beads in this strand of prayer beads measure approximately 12 mm in diameter. Photo by Sutas Singbamroong.

              We recently tested an interesting strand of Islamic prayer beads resembling amber (figure 1). It consisted of 33 round yellow beads approximately 12 mm in diameter, two oval-shaped separators, and a fancy-shaped link. It was purchased as amber from a dealer at an annual festival in Dubai.

The round beads contained dark brown plant debris and a variety of insects: ants, flies, and spiders, all in good condition. The beads’ surfaces also featured noticeable circular zones, and when exposed to long-wave UV radiation, they displayed a weak, blue fluorescence and distinctive chalky blue circular areas (figure 2). The beads were inert to short-wave UV radiation.

	Figure 2. When exposed to long-wave UV radiation, these beads displayed weak blue fluorescence and distinct, chalky blue circular areas. Photo by Sutas Singbamroong.
These features were similar to those of copal filled with plastic (Winter 2010 GNI, pp. 326–328). We obtained spot RI readings of 1.52 on the circular zones and 1.54 elsewhere. Next, we analyzed the strand using Raman spectroscopy with a 785 nm diode laser. The separator link and the main portion of the beads showed peaks between 1434 and 1644 cm–1, consistent with amber. The circular areas’ strong bands at 623, 807, 1100, and 1599 cm–1 were consistent with epoxy resin (figure 3).

	Figure 3. Raman spectra collected from the main portion of the beads were consistent with amber, whereas the circular areas indicated an epoxy resin.
Microscopic examination with immersion in water indicated that all the round beads had been cored and filled (figure 4). The beads were identified as amber filled with colorless to light yellow plastic to imitate insect-bearing amber.

	Figure 4. Microscopic observation with immersion in water clearly indicated that these amber beads had been cored and filled with a colorless to light yellow plastic containing insects. Photomicrographs by Sutas Singbamroong; magnified approximately 10×. Source: GIA @topic:14


Title: Dyed Marble as a Purple Sugilite Imitation Abstract: ABSTRACT
In the past two years, many sugilite products with a dark purple color and an obvious granular texture have appeared in the Chinese market. Sugilite pendants and bangles are very popular. Their internal texture and color distribution are inconsistent with previously documented natural specimens and suggest dyed artifacts. With that in mind, we obtained a “sugilite” bangle to investigate its gemological characteristics.

Figure 1. Testing of this bangle identified it as a dyed marble imitation of purple sugilite. Photo by Shanshan Du.
The bangle weighed about 71 grams and had a dark purple color that was distributed along the mineral grain boundaries (figure 1). Spot RIs of 1.48, 1.53, 1.57, and 1.63 were obtained from different areas of the bangle. Its hydrostatic SG was about 2.65, significantly lower than that of natural sugilite. The sample fluoresced strong purple and medium red under long- and short-wave UV radiation, respectively, which indicated treatment with organic dye(s). Five main peaks were observed in the 1600–700 cm–1 region of the FTIR spectrum (figure 2). The three peaks at 1427, 881, and 710 cm–1 are typical for calcite. The remaining two peaks at 1530 and 1505 cm–1 were believed to result from an organic dye.

Figure 2. The FTIR spectrum of the purple bangle contained characteristic peaks at 1427, 881, and 710 cm–1 that are typical for calcite.
Although the imitation resembles sugilite, its internal texture, RI, SG, fluorescence, and FTIR spectrum identify it as marble. Since marble usually occurs as a mineral aggregate with a loose texture, it is easily dyed to imitate other precious gemstones. We can therefore expect to see a steady influx of marble imitations in the market, and rigorous testing will be needed to protect consumers. Source: GIA @topic:12


Title: Quarterly Crystal: Barite in Fluorite Abstract: Figure 1. This 247.02 ct bright yellow fluorite partial crystal, which measures 40.04 mm tall, hosts two large concretions of bone-white barite. Photo by Kevin Schumacher.

Although gemologists deal primarily with fashioned gemstones, some crystal specimens are far too attractive as intact objects to be used as cutting rough. This is particularly true if they contain eye-visible inclusions like those seen in the 247.02 ct transparent yellow fluorite partial crystal shown in figure 1.

At 40.04 mm in its longest dimension, this specimen invites exploration of its inclusions, which were identified as barite using laser Raman microspectrometry. The larger of the two barites measures 7.0 mm in diameter and has a microscopically prominent rectangular purple spot on the apex of its dome (figure 2), which clearly stands out against the stark white background provided by the barite inclusion. Although the cause of the spot is unclear, the contrasting assemblage of colors adds to this specimen’s value as an aesthetic collector piece.

Figure 2. The largest of the two barite inclusions has a prominent purple spot on the top of its dome, which is easily seen against the white background provided by the inclusion. Photomicrograph by Nathan Renfro; field of view 13.71 mm. Source: GIA @topic:2


Title: Iridescent Tabasco Geode Abstract: Figure 1. This unique Tabasco geode from Mexico’s Zacatecas State, containing greenish blue botryoidal chalcedony, measures 24 mm in the longest dimension. Photo by Diego Sanchez; courtesy of Marquez Mining.
Tabasco geodes are a small geode variety named for the area where they are mined in the Mexican state of Zacatecas, near the city of Tabasco. Typically, these geodes are lined with water-clear drusy quartz, but the author recently examined one that was filled with greenish blue botryoidal chalcedony that also showed iridescent colors (figure 1). The cause of the colors was not immediately apparent, but microscopic examination revealed clues. The outermost layer of chalcedony had not firmly adhered to the underlying botryoidal mass. This delamination allowed an air gap along the interface of the thin outermost layer of chalcedony and the botryoidal mass of greenish blue chalcedony underneath. This air gap, in addition to the transparent nature of the very thin chalcedony shell, created thin-film interference colors along the interface of the chalcedony shell and substrate (figure 2). This explanation was supported by the observation that where areas of the delicate shell were damaged, the iridescence was not present. This Tabasco geode is one of the most visually interesting geodes examined by the author.

Figure 2. The Tabasco geode hosts greenish blue chalcedony, with a thin chalcedony shell that was responsible for the iridescent thin-film interference colors. Photomicrograph by Nathan Renfro; field of view 1.83 mm. Source: GIA @topic:12


Title: Quarterly Crystal: Dioptase in and on Quartz Abstract: Figure 1. Measuring 25.28 × 17.51 × 7.67 mm and weighing 15.65 ct, this colorless quartz crystal from Namibia hosts numerous transparent blue-green inclusions of dioptase. Photo by Diego Sanchez.
Crystals of transparent colorless rock crystal quartz play host to a wide variety of mineral inclusions, some of which are highly attractive. Due to its transparency and bright blue-green color, one of the most visually striking inclusions occasionally found in quartz is dioptase. Occurring in the oxidized zones of some copper deposits, dioptase gets its vibrant color from copper, the chemical formula of dioptase being Cu6Si6O18•6H2O.
Recently we had the opportunity to examine an unusual arrowhead-shaped, fully terminated colorless quartz crystal that was decorated on one side with a crust of numerous trigonal transparent dioptase crystals that were both in and on their host. The geographic source for the crystal shown in figure 1is Kaokoveld, Namibia. Weighing 15.65 ct and measuring 25.28 × 17.51 × 7.67 mm, this unusual example of rock crystal plays host to numerous near-surface trigonal crystals (figure 2) up to 3.0 mm in length.

Figure 2. Trigonal blue-green crystals in and on the surface of this colorless quartz were identified by Raman analysis as dioptase. Photomicrograph by Nathan Renfro; field of view 11.75 mm.
The visual characteristics of the features—the trigonal micromorphology, degree of transparency, and color of the numerous inclusions—suggested dioptase; this was confirmed using laser Raman microspectrometry. The euhedral dioptase inclusions were situated on only one side of the quartz, which illustrates that they developed through directional deposition late in the quartz growth cycle. Source: GIA @topic:2


Title: “Double Bubble” Multiphase Inclusion in Beryl Abstract: Figure 1. A 64.10 ct pale green rough beryl crystal containing noteworthy multiphase inclusions. Photo by Robison McMurtry.
Beryl often hosts multiphase inclusions consisting of all possible combinations of solid, liquid, or gas inclusions. These remnants of the growth environment become trapped within negative crystals during formation. The fluid is trapped as a homogenous liquid that separates into component phases during cooling. Jagged three-phase inclusions commonly found in Colombian emeralds are perhaps the most well-known multiphase inclusions in beryl.

Figure 2. Photo series of a prismatic multiphase inclusion displaying a “double bubble” of gas within gas at room temperature (left). The smaller bubble shrinks by about half after approximately 45 seconds of exposure to the microscope well light (center) and completely homogenizes after about a minute (right). Photomicrographs by Hollie McBride; field of view 2.34 mm.
A 64.10 ct pale green rough beryl submitted by L. Allen Brown (All That Glitters, Methuen, Massachusetts) contained a plethora of prismatic three-phase negative crystals with a notable suite of gas bubbles, several species of extremely small daughter crystals, and an aqueous solution (figure 1). At room temperature, the gas phases were out of equilibrium with each other, which gave rise to a “double bubble” nested appearance: a gas bubble within a second, larger gas bubble. Over the course of about a minute, the gentle heat of the microscope well light warmed the smaller gas bubble enough to completely homogenize with the larger bubble so that only one bubble remained (figure 2). Source: GIA @topic:3