Читать книгу Geology and Mineralogy of Gemstones - Karl Wallace, David Turner R. - Страница 4

1 Chapter 1Figure 1.1 An atomic model of the element helium (He), with two protons, two...Figure 1.2 An atom can lose electrons and become a cation, a positively char...Figure 1.3 Periodic table of the elements with atomic numbers and chemical a...Figure 1.4 Relative abundance of the elements in the Earth's crust as compar...Figure 1.5 This crystal of corundum shows rhombohedral parting patterns and ...Figure 1.6 This cluster of bladed kyanite crystals shows brittle tenacity an...

2 Chapter 2Figure 2.1 The Earth System. A schematic model of the Earth as a series of i...Figure 2.2 Simplified schematic of the Earth’s principal internal geological...Figure 2.3 The major tectonic plates of the Earth, their boundaries, and rel...Figure 2.4 This cross‐section illustrates the main types of plate boundaries...Figure 2.5 Schematic diagrams of (a) continental–continental convergent plat...Figure 2.6 Map and aerial view of the San Andreas Fault that cuts across the...Figure 2.7 Thickness contour map of the of the Earth's crust, developed from...Figure 2.8 Simple and generalized classification diagram for igneous rocks, ...Figure 2.9 Simple and generalized classification diagram for sedimentary roc...Figure 2.10 Simple diagram for metamorphic rocks based on changing temperatu...Figure 2.11 Simple diagram for metamorphic rock descriptions based primarily...Figure 2.12 This schematic of the Rock Cycle illustrates some of the most co...Figure 2.13 Idealized schematics of fluid flow through the Earth’s crust wit...Figure 2.14 Schematics of three fault types: reverse, normal, and strike‐sli...Figure 2.15 Schematics of three folding patterns of layered rocks. Here, the...Figure 2.16 Faulting (red dashed line) and folding (yellow dashed line) in l...Figure 2.17 Schematic diagram of diamonds hosted in kimberlite pipes that ar...

3 Chapter 3Figure 3.1 Shapes of different unit cells of crystal systems, as defined by ...Figure 3.2 The top row shows polyhedra from example minerals, the bottom row...Figure 3.3 Crystal structure of beryl visualized using polyhedra (top row) a...Figure 3.4 Anatomy and equation of a wave.Figure 3.5 The refraction and interaction of light between two media: air an...Figure 3.6 The refractive indices for various materials across the visible r...Figure 3.7 The visible portion of the electromagnetic spectrum with Fraunhof...Figure 3.8 Incident light can refract and reflect (red rays) if the angle of...Figure 3.9 Electromagnetic spectrum labeled with representative colors. Wiki...Figure 3.10 Examples of light reflecting off different surfaces. Image from ...Figure 3.11 Additive (left) and Subtractive (middle) Color Theory Diagrams (...Figure 3.12 Light output from three sources of electromagnetic radiation. No...Figure 3.13 Example spectra of light output from different “colored” LEDs (a...Figure 3.14 The “color change effect” exhibited by a single 17.08 carat alex...Figure 3.15 Plot showing the change of diamond’s refractive index as a funct...Figure 3.16 Schematic of a prism with light refracting after passing through...Figure 3.17 This large 898 carat faceted cerussite (PbCO₃) from Namibia, kno...Figure 3.18 Double refraction of lines drawn on paper as viewed through a si...Figure 3.19 Titanite is a rare gem mineral (but common mineral) that has a h...Figure 3.20 Peridot (left) and turquoise (right) are common idiochromatic ge...Figure 3.21 The Gachala Emerald (858 carats) from Colombia is an example of ...Figure 3.22 Very large calcite gem (1,865 carats) from St. Joe #2 Mine, Balm...Figure 3.23 Six‐rayed star in ruby (left) and chrysoberyl (right) from Sri L...Figure 3.24 Sunstone (left) showing strong iridescence from light scattered ...Figure 3.25 Pleochroism in a synthetic sapphire, as viewed with a polaroid‐p...Figure 3.26 Pleochroism in a tourmaline cut with the c‐axis parallel to the ...Figure 3.27 Transparent specimen of pink zoisite. Smithsonian National Museu...Figure 3.28 These sunstones from Oregon, USA, show varying degrees of transp...Figure 3.29 This piece of carved imperial jadeite from Burma (13.7 carats) s...Figure 3.30 Turquoise is a common semitranslucent to opaque gemstone. Specim...

4 Chapter 4Figure 4.1 An example of critical angles using quartz and diamond of equival...Figure 4.2 Conventional 10× loupe.Figure 4.3 Rock hammers are necessary tools for field geology and are useful...Figure 4.4 Dichroscope (right) and view through the dichroscope (left) of a ...Figure 4.5 Shortwave UV lamp (left) with peak output at ~254 nm and (right) ...Figure 4.6 A GIA refractometer. The stone sits in a holder within the small ...Figure 4.7 Binocular microscope with flexible fiber‐optic light sources.Figure 4.8 Example spectrum of emerald as viewed through a spectroscope. Wit...Figure B4.1.1 An example of cesium (Cs) and lithium (Li) chemical compositio...Figure 4.9 Spectral absorbance plot of emerald showing strong absorption in ...Figure 4.10 Infrared spectra of natural and synthetic amethyst from 3,640 to...Figure 4.11 Polarizing microscope and polarized photomicrograph of a zircon ...Figure 4.12 Binocular confocal microscope for nondestructive Raman spectrosc...Figure 4.13 Raman spectra of diamond and two common simulants. Each pattern ...

5 Chapter 5Figure 5.1 The Vallerano Diamond, found during excavations of a ~150 BCE tom...Figure 5.2 A map showing the positions of the various holdings at Kimberley ...Figure 5.3 Uncut (rough) diamond octahedron (left) and cut (polished) diamon...Figure 5.4 Thermal conductivities of some materials commonly encountered in ...Figure 5.5 Fluorescence of cut and rough diamonds under normal (left) and UV...Figure B5.1.1 Crystal structures of diamond (left) and graphite (right). Dia...Figure 5.6 Diamond’s crystal structure looking along a crystallographic axis...Figure 5.7 Classification of diamonds based on crystal chemistry. Breeding a...Figure 5.8 The basic shape of an octahedral diamond (left) and more complex ...Figure 5.9 Diamond octahedron (left) and diamond macle (right), as exhibited...Figure 5.10 Secondary shapes through increasing degrees of magmatic resorpti...Figure 5.11 An octahedral diamond like this one could have undergone some re...Figure 5.12 Yellow‐tinted diamond with resorption and stepped growth feature...Figure 5.13 This diamond grew initially as an unincluded (clean) crystal but...Figure 5.14 Yellow diamonds (left) from rough starting material to the oval ...Figure 5.15 Pink and colorless diamond octahedrons from the Argyle Mine in A...Figure 5.16 The DeYoung Red Diamond is of the finest red color and large siz...Figure 5.17 “Chameleon Diamond” that shows green coloration before heating a...Figure 5.18 The ~41 carat Dresden Green Diamond housed in the Green Vaults o...Figure 5.19 Before (left) and after (center) HPHT treatment of a Type IIa di...Figure 5.20 This figure shows a full range of colors that can be produced in...Figure 5.21 Mineral inclusions in diamonds may be removed or lightened by la...Figure B5.2.1 Photomicrographs of pyrope garnet inclusion (~0.15 mm wide) wi...Figure B5.2.2 Photographs of gem rough with mineral inclusions suitable for ...Figure B5.2.3 Sapphirine (left) and cordierite (right) solid mineral inclusi...Figure 5.22 Schematic vertical section through the Earth’s crust and part of...Figure 5.23 This Temperature–Pressure diagram highlights the relationship be...Figure 5.24 Morphology of a classical kimberlite diatreme, or pipe, with oth...Figure 5.25 The plan views (top) and vertical side views (bottom, also known...Figure 5.26 This figure shows the plan view (top) and vertical side view (bo...Figure 5.27 This figure shows a 3D cross‐section of one of the Ekati diamond...Figure 5.28 Compositional CaO vs. Cr₂O₃ diagram for garnet inclusions within...Figure 5.29 The Australian Argyle diamond mine, showing aerial imagery drape...Figure 5.30 Schematic cross‐section of the Argyle AK1 diamondiferous lamproi...Figure 5.31 Waste rock dumps at the Argyle diamond mine, Western Australia. ...Figure 5.32 Distribution of 16 Archean cratons (red) underlain by Precambria...Figure 5.33 Global rough diamond production by carat weight (not value) from...Figure 5.34 Global rough diamond production by carat weight (not value) from...Figure 5.35 Percentages of world diamond production by country by year in te...Figure 5.36 Distribution of clusters of diamond‐bearing kimberlite in Canada...Figure 5.37 The Diavik Diamond Mine and kimberlite cluster in Lac de Gras, N...Figure 5.38 Diamonds from Diavik Diamond Mine are found as perfect octahedra...Figure 5.39 Fancy yellow diamonds (left 46.5 ct, right 23.9 ct) with slightl...Figure 5.40 Macro diamond found in drill core (center of drill core) from th...Figure 5.41 Simplified anatomy and facet names of a round brilliant‐cut diam...Figure 5.42 This schematic of a Princess‐cut diamond has a perfectly proport...Figure 5.43 Drawings of diamonds showing light paths into and out of each of...Figure 5.44 Clarity scale for diamonds.Figure 5.45 Color grading scale for diamonds.Figure 5.46 Emerald cut (left, 2.02 carats) and marquise cut (right, 2.44 ca...Figure 5.47 Example prices in US$1,000 per carat by color according to clari...Figure 5.48 Price in US$1,000 per carat according to carat size and color. R...

6 Chapter 6Figure 6.1 The Kitaa Ruby from Greenland is possibly the largest ruby ever f...Figure 6.2 Ball and stick representation of corundum’s crystal structure, lo...Figure 6.3 Rubies from Greenland showing a tapered bipyramidal barrel shape....Figure 6.4 This large sapphire from Baffin Island, Nunavut, shows an elongat...Figure 6.5 This ruby crystal shows a rough hexagonal outline with a squat cr...Figure 6.6 Oscillatory zoned blue (left) and Padparadscha (right) sapphire c...Figure 6.7 These rubies and pink sapphires have an assortment of cuts and ra...Figure 6.8 The rough and two carved sides of the Kitaa Ruby. Original weight...Figure 6.9 The Carmen Lúcia ruby, a spectacular 23.1 carat stone from Burma,...Figure 6.10 Three deeply colored sapphires from the Beluga Occurrence, Baffi...Figure 6.11 Rutile fibers (also known as “silk”) in a faceted blue sapphire ...Figure 6.12 These two yellow sapphires from the Beluga Occurrence, Baffin Is...Figure 6.13 Black star sapphire showing typical asterism as a result of orie...Figure 6.14 Reeves Star Ruby (left, 138.7 carats, from Sri Lanka) and star s...Figure 6.15 Two views of an irregularly zoned sapphire from Baffin Island, N...Figure 6.16 This photo shows a blue‐violet example of the cornflower plant t...Figure 6.17 An example parcel of “before” (left) and “after” (right) heat tr...Figure 6.18 Pressure–temperature ranges for various global metamorphic gem c...Figure 6.19 Example of sapphire‐bearing marble in outcrop, Baffin Island, Ca...Figure 6.20 Marble‐hosted “gemmy” pink sapphire crystal from British Columbi...Figure 6.21 Trace element chemistry of ruby and pink sapphire from selected ...Figure 6.22 Basaltic fields of Central and East Asia through to Australia of...Figure 6.23 Simplified genetic model for alkali basalt‐hosted corundum. Coru...Figure 6.24 Xenocrystic corundum examples from Cenozoic‐aged alkali basalts ...Figure 6.25 These sapphires originated from Yogo Gulch and range in size fro...Figure 6.26 Alluvial sapphires and red corundum from Australia. (a) View of ...Figure 6.27 Photograph of an exposed paleochannel from the Mugloto Area of t...Figure 6.28 Alluvial artisanal gem washing in Madagascar. Photo by V. Pardie...Figure 6.29 Examples of exceptional corundum gemstones. Left: In the collect...Figure B6.1.1 Geology of the Island of Naxos (Urai & Feenstra, 2001 ...Figure B6.2.1 Geological map showing the location and geological setting of ...Figure B6.2.2 Rudimentary yet effective mine workings pepper the landscape. ...Figure B6.2.3 Ruby (left, ~1.5 cm) and spinel (right) hosted in soft marble ...

7 Chapter 7Figure 7.1 The faceted and carved Dom Predo Aquamarine (10,363 carats, from ...Figure 7.2 Crystal structure of beryl looking just off the c axis, along the...Figure 7.3 Crystal structure of beryl looking perpendicular to the c axis; n...Figure 7.4 Diagram of substitutions for aluminum by various cations, shown a...Figure 7.5 These phenomenal 15,256 carat unheated rough and 1,000 carat face...Figure 7.6 These red beryl crystals on altered rhyolite matrix are from the ...Figure 7.7 This cluster of aquamarine crystals are from Pakistan and exhibit...Figure 7.8 This morganite crystal from Pala (California) shows a common form...Figure 7.9 These heliodor crystals on matrix (host rock) show excellent tran...Figure 7.10 This dark blue beryl crystal shows good clarity in the deeper to...Figure 7.11 This faceted dark blue beryl crystal is the same crystal as that...Figure 7.12 This piece of rough euhedral emerald originates from the Ghost L...Figure 7.13 Gem‐quality euhedral emerald crystal hosted in calcite from Cosc...Figure B7.1.1 Left: Relative strengths of light absorbance (light being lost...Figure 7.14 These cut beryl specimens range in weight from 911 to 2,054 cara...Figure 7.15 The “Chalk Emerald” from Colombia is large at 37.8 carat and is ...Figure B7.2.1 The Mogul Emerald. Keller (1981) / with permission of Gemologi...Figure B7.2.2 The Hooker Emerald. Smithsonian National Museum of Natural His...Figure 7.16 Open pit mining at the Kagem Emerald Mine in Zambia. Photo from ...Figure 7.17 Cross‐section and internal structure of a complex pegmatite, not...Figure 7.18 An hypothetical magma and some of the mechanisms by which beryl ...Figure 7.19 The interaction of hot magmatically‐derived hydrothermal fluids ...Figure 7.20 Green emerald crystals hosted in white quartz vein from the Tsa ...Figure 7.21 Schematic formation model of red beryl at the Ruby Violet Mine, ...Figure 7.22 This specimen of red beryl was fractured at some point in its ge...Figure 7.23 Geographic distribution of main emerald deposits (green circles ...Figure 7.24 This emerald specimen, still in its host rock, is also from Colo...Figure 7.25 Local geological setting (a) of emerald deposits from the Wester...Figure 7.26 These emeralds (~5–23 carats) from Penas Blancas mine in Colombi...Figure 7.27 Geological cross‐section (left) at Habachtal, Austria, and simpl...

8 Chapter 8Figure 8.1 Three photos showing ranges of scale for pegmatites, from small (...Figure 8.2 Schematic representation of regional geochemical zoning in pegmat...Figure 8.3 Trace element composition of potassium feldspar from the Luumaki ...Figure 8.4 Schematic drawings of simple to complex pegmatites. (a) is a simp...Figure 8.5 Mapped vertical cross‐section of a tourmaline‐bearing pocket from...Figure 8.6 Cross‐section and zoning patterns seen in a complex pegmatite dyk...Figure 8.7 Geological map (left, a) and cross‐section (left, b) of the Luuma...Figure 8.8 Partially corroded beryl (var. aquamarine) crystal. Corbin17 / Al...Figure B8.1.1 Oxygen isotope values in corundum showing that certain types o...Figure B8.1.2 Boron isotope compositions in a variety of geological settings...Figure B8.1.3 Trace element compositions of bismuth, lead, and gallium for c...Figure B8.1.4 Laser induced breakdown spectroscopy (LIBS) is being increasin...Figure 8.9 These crystals of black schorl are hosted in quartz veins cutting...Figure 8.10 Slice of watermelon tourmaline with euhedral shape alongside the...Figure 8.11 Elbaite tourmaline (var. indicolite) on quartz matrix from Minas...Figure 8.12 Crystal structure of tourmaline looking just off the c axis (lef...Figure 8.13 Part of the tourmaline mineral species classification scheme bas...Figure 8.14 Examples of color in the tourmaline group of minerals, although ...Figure 8.15 Two examples of the mineral elbaite but showing different colors...Figure 8.16 Canary yellow tourmaline (fluor‐elbaite) from eastern Zambia, 50...Figure 8.17 Green tourmaline set with platinum and diamonds. Photo by D. Tur...Figure 8.18 Rubellite variety of gem tourmaline with heavy purple overtone. ...Figure 8.19 Color‐zoned elbaite from Antananarivo, Madagascar (left) and an ...Figure 8.20 Three examples (top) of Paraíba‐type tourmaline from Brazil, Nig...Figure 8.21 These two plots show the absorption spectra in the visible‐to‐ne...Figure 8.22 Faceted and rough prismatic spodumene crystal. Note the roughly ...Figure 8.23 Crystal structure of spodumene, a lithium‐ and aluminum‐bearing ...Figure 8.24 Photograph of the Etta Mine in South Dakota circa 1904 (top) fro...Figure 8.25 Kunzite weighing 104.66 carats from Brazil. Photo from Royal Ont...Figure 8.26 Left: spodumene in unpolarized “normal” light, as your eye would...Figure 8.27 Green hiddenite specimen from North Carolina, USA (left), is 4.6...Figure 8.28 Crystal structure of topaz looking slightly oblique down the c a...Figure 8.29 The faceted stone “American Golden Topaz” (left), 22,892.5 carat...Figure 8.30 Natural blue topaz, ~4 cm tall, on albite and micas from Mursink...Figure 8.31 Simplified geological map of the Klein Spitzkoppe topaz‐bearing ...Figure 8.32 Schematic of topaz‐bearing rhyolite dome and flows. Note the occ...Figure 8.33 Euhedral topaz crystals (~2 cm) formed in lythophysae (gas cavit...Figure 8.34 Microphotograph of euhedral topaz crystals in quartz‐calcite vei...Figure 8.35 Cognac‐colored Imperial topaz (left), 875.4 carats rough, 94 car...Figure 8.36 Gold ring with pink topaz and diamonds. Locality unknown.

9 Chapter 9Figure 9.1 The crystal structure of chrysoberyl, showing BeO₄ tetrahedra in ...Figure 9.2 Cat’s eye chrysoberyl from gem placers in New South Wales, Austra...Figure 9.3 This chrysoberyl gemstone is from Minas Gerais (~115 carats) and ...Figure 9.4 The Whitney Alexandrite from Minas Gerais – possibly one of the f...Figure 9.5 Deposit model schematic for the pegmatite‐related Franqueira (Spa...Figure 9.6 Regional geological map (upper left, A) and geologic vertical cro...

10 Chapter 10Figure 10.1 The Imperial State Crown of the United Kingdom prominently displ...Figure 10.2 The crystal structure of spinel, with MgO₄ tetrahedra in orange ...Figure 10.3 A collection of spinel of various colors from the Luc Yen area, ...Figure 10.4 Blue spinel colored by cobalt from Baffin Island (Nunavut, Canad...Figure 10.5 Faceted and rough spinel from Mogok (Myanmar, formerly Burma), w...Figure 10.6 Marble‐hosted red spinel from the Luc Yen area, Vietnam. Van Lon...Figure 10.7 Scanning electron microscope images of a spinel crystal hosted i...Figure 10.8 Geological map of the Luc Yen area (Vietnam) with primary in sit...Figure 10.9 Schematic of spinel (blue) formation in marbles of the Luc Yen a...Figure 10.10 Oxygen isotope values for purple, pink, red, blue, and orangy s...

11 Chapter 11Figure 11.1 Crystal structure of zoisite (parent mineral of tanzanite), with...Figure 11.2 Tanzanite with fantastic deep violet‐blue color and weighing 122...Figure 11.3 Tanzanite before (left) and after (right) heat treatment, with g...Figure 11.4 Location of the tanzanite deposits in the Merelani Hills. Olivie...Figure 11.5 Schematic 3D diagram of tsavorite mineralization environments wi...Figure 11.6 The four mining blocks that host tanzanite mineralization. Block...

12 Chapter 12Figure 12.1 Left: rough (43.30 carats) and cut (13.88 carats) pink pyrope, l...Figure 12.2 Crystal structure of spessartine, Mn₃Al₂(SiO₄)₃, looking down th...Figure 12.3 Left: fire‐red Bohemian chromium‐bearing pyrope garnet (Schlüter...Figure 12.4 Geological schematic for the formation and subsequent transport ...Figure 12.5 Ternary plots of garnet compositions and probable provenance fro...Figure 12.6 Green demantoid (andradite) garnets set with diamonds and white ...Figure 12.7 Green demantoid (chromium‐bearing andradite) garnets from the Ur...Figure 12.8 Genetic models for tsavorite garnet nodule formation in the Moza...Figure 12.9 Fine lamellae in iridescent garnet from Nara Prefecture, Japan (...Figure 12.10 Pink (incandescent) to purple (LED) color‐change pyrope garnet....Figure 12.11 Color‐change characteristics of a selection of vanadium‐bearing...

13 Chapter 13Figure 13.1 The crystal structures of jadeite (left, a pyroxene group minera...Figure 13.2 White nephrite jade disc (~5.5 cm across) from Qing Dynasty. Its...Figure 13.3 This piece of carved jade weighs 13 carats and is of top quality...Figure 13.4 Blue jadeitite from the Motagua River area of Guatemala, often r...Figure 13.5 Generalized formation model for jadeitite deposits from Harlow e...Figure 13.6 Cross‐section (and thin section sketch) through a jadeitite vein...Figure 13.7 Global distribution of jadeitite deposits with the trace of plat...Figure 13.8 Schematic of altered argillite with rind of seminephrite and act...Figure 13.9 Schematic of nephrite associated with dolomitic marble at the Ch...Figure 13.10 A map of the distribution of jade throughout British Columbia. ...Figure 13.11 Outcrop photographs from Devine et al. (2004) of the Arctic Kin...Figure 13.12 Nephrite jade artifacts recovered in Alberta (Canada), with ori...Figure 13.13 Map of jade localities along the South Island of New Zealand on...Figure 13.14 Rubidium and strontium stable isotope characteristics of nephri...

14 Chapter 14Figure 14.1 This collection of quartz gems exhibits a variety of cutting sty...Figure 14.2 The crystal structure of quartz looking approximately down the cFigure 14.3 Some quartz crystals occur in a “doubly terminated” form, where ...Figure 14.4 This cluster of quartz crystals from Arkansas stands ~45 cm tall...Figure 14.5 Amethyst geode (left) from Brazil showing concentric zoning that...Figure 14.6 Geological cross‐section schematic of lava flows belonging to th...Figure 14.7 Cluster of amethyst crystals from the Anahi Mine in Bolivia, sta...Figure 14.8 This amethyst pendant (~96 carats) shows excellent color. Howeve...Figure 14.9 Thunderegg geode cut through its center to reveal a variety of f...Figure 14.10 Polished and rough Australian opal from the Barcoo River area, ...Figure 14.11 High magnification scanning electron microscope images of opal’...Figure 14.12 Schematic cross‐section of the geological setting for precious ...Figure 14.13 Regional geological setting of geological units relevant for op...Figure 14.14 Fingerprinting of opal from Australia using a multi‐element dat...Figure 14.15 Geochemical fingerprinting of 77 opal samples from global local...Figure 14.16 Proposed model of digit formation in opal and example cross‐sec...

15 Chapter 15Figure 15.1 This collection of peridot gems range in weight from 3 to 311 ca...Figure 15.2 This peridot gem of fine color (bright green, little yellow unde...Figure 15.3 The crystal structure of forsterite, with SiO₄ tetrahedra in blu...Figure B15.1.1 Example of polished pallasite with gemmy portions of peridot ...Figure B15.1.2 Trace element distinction diagrams by Shen to differentiate t...Figure 15.4 Lily‐pad inclusion in San Carlos (New Mexico) peridot at 45× mag...Figure 15.5 Peridotite mantle xenolith nodules hosted in tertiary‐aged basal...Figure 15.6 Geological map of Zabargad, noting the location of gem peridot i...Figure 15.7 Euhedral crystal of peridot from Zabargad, measuring 4 cm across...Figure 15.8 Turquoise in host rock matrix and as finished and polished gemst...Figure 15.9 The crystal structure of turquoise, with PO₄ tetrahedra in purpl...Figure 15.10 Nodular turquoise. Photos from Keller (1990) and Chen et al. (2...Figure 15.11 Stable isotope plots of turquoise samples from a range of local...Figure 15.12 This carving of lapis lazuli from Afghanistan shows the deep co...Figure 15.13 A seam of lapis lazuli in an outcrop (left) and a close‐up phot...Figure 15.14 Geological setting of lapis lazuli mineralization near the Sope...Figure 15.15 Geology of lapis lazuli mineralization at Malaya Bystritsa, Bai...Figure 15.16 First‐ to fourth‐quality lapis and reject material from the Chi...Figure 15.17 Annotated photograph of the Chilean skarn‐related lapis lazuli ...Figure 15.18 Flow chart for provenance discrimination of lapis lazuli when c...Figure 15.19 Heat treated blue zircon (5.96 carats) from Cambodia – doubling...Figure 15.20 The crystal structure of zircon, with SiO₄ tetrahedra in blue a...Figure 15.21 Distribution of gem‐quality zircon hosted in <30 Ma alkali basa...Figure 15.22 Distribution of Cenozoic alkali basalts in Southeast Asia, an i...Figure 15.23 Euhedral gemmy zircon xenocryst (7 × 4.5 × 4 mm) in host basalt...Figure 15.24 Rough zircon from Cambodia before (left) and after (right) heat...Figure 15.25 Schematic showing alkali basalt formation in the Lava Fields ar...Figure 15.26 Prismatic zircon crystal showing double termination and square ...Figure 15.27 Simplified geological map (top) of the Reichsforst and Teichelb...

16 Chapter 16Figure 16.1 Global distribution of important amber localities. Yellow is Ter...Figure 16.2 Polished Baltic amber beads showing a range of common colors fro...Figure 16.3 Geological setting (a) and stratigraphic column (b) of amber dep...Figure 16.4 Type 1 (left, fractured) and Type 2 (right, sheet) ammolite, wit...Figure 16.5 Location map of the St. Mary River Valley with working ammolite ...Figure 16.6 Type 2 ammolite with very well preserved ammonite shell, ~45 cm ...Figure 16.7 Microstructure of ammolite as seen under a scanning electron mic...Figure 16.8 Example of a “triplet” composite gemstone: (B)acking of dark opa...