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86 Cards in this Set
- Front
- Back
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Environment of Formation: Diamond |
Kimberlite (volcanic) |
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Environment of Formation: Sapphire |
Corundum Gneiss, Schist (Metamorphic) |
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Environment of Formation: Ruby |
Corundum Gneiss, Schist (Metamorphic) |
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Environment of Formation: Emerald |
Beryl Granitic Pegmatite or Schist (Metamorphic) |
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Environment of Formation: Peridot |
Olivine Basalt (volcanic), Gabro (intrusive igneous) |
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Environment of Formation: Garnet |
Gneiss, Schist (metamorphic) |
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Environment of Formation: Topaz |
Granitic Pegmatite |
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Environment of Formation: Aquamarine |
Beryl Granitic Pegmatite |
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Environment of Formation: Tourmaline |
Granitic Pegmatite |
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Environment of Formation: Jadeite |
Pyroxene High temp, high pressure, metamorphics |
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Environment of Formation: Nephrite |
Tremolite amphibole Metamorphosed Dolomitic Limestone |
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Environment of Formation: Moonstone |
Orthoclase Granite and Related Igneous Rocks |
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Environment of Formation: Sunstone |
Oligoclase Granite and Related Igneous Rocks |
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Environment of Formation: Labradorite |
Gabbo (Igneous Rock) |
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Environment of Formation: Kunzite/Hiddenite |
Spodumene Lithium-rich Granitic Pegmatite |
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Environment of Formation: Lapis Lazuli |
Lazurite Contact-Metamorphosed Limestones |
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Environment of Formation: Quartz (Amethyst) |
Igneous Rocks and Hydrothermal Zones |
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Environment of Formation: Spinel |
Metamorphosed Limestones and Clay-Rich Rocks |
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Environment of Formation: Chrysoberyl |
Granitic Pegmatites and Mica Schists |
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Environment of Formation: Pearl |
Live Mollusc |
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Environment of Formation: Shell |
Live Mollusc |
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Environment of Formation: Rhodochrosite |
Hydrothermal Veins in Metal Ore Bodies |
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Environment of Formation: Malachite |
Veins in Copper Deposits associated with Limestones |
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Environment of Formation: Azurite |
Veins in Copper Deposits associated with Limestones |
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Environment of Formation: Apatite |
Igneous, Sedimentary, and Metamorphic Rocks |
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Environment of Formation: Turquois |
Decomposed Volcanic Rocks in Arid Conditions |
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Environment of Formation: Tortoise Shell |
Live Sea Turtle |
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Environment of Formation: Amber |
Fossil Trees in any Sediment or Sedimentary Rock |
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Country of Origin: Emerald |
Colombia, Zambia, Zimbabwe |
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Country of Origin: Sapphire and Ruby |
Thailand, Myanmar (Burma), Sri Lanka |
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Country of Origin: Topaz |
Brazil, Pakistan |
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Country of Origin: Spinel |
Myanmar, Sri Lanka, Tanzania, Afghanistan, Thailand, Russia |
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Country of Origin: Diamond |
Australia, Canada, Zaire (Congo), Russia, South Africa, Botswana, Sierra Leone |
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Country of Origin: Garnet |
Tanzania, India, Sri Lanka |
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Country of Origin: Tourmaline |
Russia, Brazil, Madagascar, Nigeria |
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Country of Origin: Amethyst |
Brazil, Uruguay, Zambia |
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Country of Origin: Turquois |
Iran, Arizona, China |
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Igneous Rock-Hosted Gemstones |
Orthoclase (Moonstone) Oligoclase (Sunstone) Labradorite Olivine (Peridot) Diamond |
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Pegmatite Minerals |
Beryl (Emerald, Aquamarine, all Beryls) Topaz Quartz (Citrine, Amethyst, Smoky) Spodumene (Hiddenite, Kunzite) Tourmaline (Rubellite, Green/Watermelon Tourmaline) Apatite |
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Igneous and Pegmatite Process |
1. Have hot silicate liquid surrounded by cooler country rock - > Cooling Begins 2. First formed crystals float in hot liquid - > Near final cooling of silicate liquid 3. First formed crystals have grown larger, different crystals forming later (different minerals, different compositions) - > Final stage of cooling - millions of yrs later 4. Appearance of pools of volatile components (water, CO2 and incompatable elements). Pools are sources of crystallization of minerals |
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Pegmatite |
Cavity near edge of cooling rock mass which fills with large crystals Pegmatic Gemstones: slow crystallization from aqueous and gaseous emanation aids growth of large crystals in cavity Pegmatic Gemstones are formed with major elements from cooling melt plus in compatible elements not used for formation of major mineral phases |
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Metamorphic Rock |
Sedimentary rocks that have undergone high temperature and pressure |
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Metamorphic Aureole |
Occurs between granite magma and unaltered limestone - 2 layers: 1. Calcite + Chlorite + Serpentine 3. Garnet + Diopside |
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Progressive Metamorphism |
Deeper = higher pressure and higher grade |
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Diagenesis - Metamorphic |
Shale (sedimentary |
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Low-Grade Metamorphic |
Slate |
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High- Grade Metamorphic |
Phyllite (metamorphic) Schist, Gneiss |
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Shale turns into what metamorphic rock(s) |
1. Slate 2. Phyllite 3. Schist 4. Gneiss |
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Sandstone turns into what metamorphic rock(s) |
Quartzite |
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Limestone turns into what metamorphic rock(s) |
Marble |
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Basalt turns into what metamorphic rock(s) |
Hornfels |
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Metamorphic Silicate Minerals |
Garnet Emerald |
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Metamorphic Oxide Minerals |
Sapphire Ruby |
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Silicate Rock Gemstones |
Jade Jadeite |
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Calcium Silicate Minerals |
Nephrite |
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Sedimentary Rocks |
Formed from sediments being transported by wind, water, ice and then are compacted and cemented (lithified) |
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Clastic Rocks |
Conglomerate (cemented gravel) Sandstone Shale (mudstone- cemented silt and clay) |
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Chemical Precipitates/Bioclastic Debris |
Limestone Halite |
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Formation of Opal in Sandstone |
Si and O are worked into pore space - transported by water percolating down Si begins to build small spheres of amorphous SiO2 |
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Sedimentary Material |
Turquois - Copper Carbonate - Other colours that appear in turquois stone come from host stone matrix - Comes from arid climate |
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Charge Transfer in Corundum |
Adjacent octahedral units containing Al and O Iron and Titanium substitute for Al electron from Fe2+ jumps to Ti4+ Fe2+ -> Fe3+ Ti4+ -> Ti3+ |
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3 Types of Charge Transfers |
1. Metal-Metal: Fe and Ti 2. Nonmetal-Metal: O2- for Cr6+, V5+, Fe3+ 3. Electrons not on Metal |
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Colouration in Minerals by Colour Centers |
Colour center: generic term for a defect that causes light absorption - Particularly one affected by irradiation (defect is charged - increased light absorbed) |
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Types and Examples of Colour Center Defects |
1. Missing atoms (vacancies) - carbon vacancies cause green diamonds
2. Intersitial Sites: 2 atoms on single site - sodalite blue - 2 oxygens
3. Impurity Molecules: Co3- molecule in blue maxixe beryl
4. Atoms substitute for major elements: hole on AlO4 molecule - grey quartz |
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SUWA System of Quality and Value of Gemstone |
Determined by 7 factors: 1. Mineral species type 2. Country of origin 3. Presence/absence/degree of treatment 4. Beauty 5. Colour Tone 6. Defects 7. Size |
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Assessment of Beauty of Gemstone |
S: Especially beautiful and brilliant A: Very beautiful B: Beautiful C: Imperfections but beautiful D: Lacking in beauty |
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Assessment of Colour of Gemstone |
1 (lightest) - 7 (darkest) |
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4 C's for Choosing a Diamond |
1. Colour 2. Cut 3. Carat weight 4. Clarity |
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Band Gap Energy and Resulting Colours |
Case A: bottom of conduction band higher than visible light range: no visible light absorbed - colourless
Case B: bottom of conduction band within the visible: some visible light absorbed - colour transmitted not in range not absorbed
Case C: bottom of conduction band lower than visible light range - all colour absorbed |
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Case C Special Case Metals |
Tiny band gap or no band gap at all- all light absorbed but because their electrons quickly return to their original energy level, emit same energy as absorbed, giving it a metallic lustre
Gold: efficiently absorbs and re-emits yellow
Silver/Platinum: efficient at all wavelengths - emit white |
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Colour in Opal |
Colour of deffracted light depends on deffracting spheres |
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Differential Refraction due to Layer Sizes |
Common in gem feldspars Equal spacing: results in blue Unequal: red |
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Pearls |
Irridescence: transmission through and reflection from boundaries in alternating layers of aragonite and conchiolin
Orient: interference colours don't cover entire surface of pearl
Overtone: interference colours do cover entire surface of pearl |
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Basics of Dispersed Metal Ion Colour |
- Colour affected by identity of dispersed metal ion (chromophore) - Also by valence state of dispersed metal ion - Also be neighbouring atoms (usually oxygen) near dispersed metal ion - Geometry of surrounding neighbouring atoms can affect colour - also called the coordination (octahedral, tetrahedral, cubic, distorted versions of any of these) |
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Most Commonly Encountered Dispersed Ions that Cause Colours |
Titanium Vanadium Manganese Iron Cobalt Copper Nickle Chromium |
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General Rule of Dispersed Metal Ion Colour |
Different charge on same element = different hue of colour |
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Beryl Dispersed Metal Ion |
Mn2+: delicate pink in morganite Mn3+: intense red in red beryl Fe3+: yellow Fe2+: blue Emerald: special green produced by Cr3+ |
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Garnet Dispersed Metal Ion |
Garnet shows 3 metal ion coordination environments - metal ion surrounded by oxygen in each case Cobalt 2+: blue in spinel, pink in cobaltocalcite Fe2+: green in peridot, red in pyrope - almandine garnet
all these show how different coordination of environment of a single dispersed metal ion produces different colours even though oxygen surrounds metal in all 4 cases |
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Electrostatic repulsion of metal ions occur with varying intensity depending upon proximity of orbital metal ion wrt the oxygen |
Intense: orbital points directly at oxygen atom Less Intense: orbitals point between oxygen atoms |
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Ruby vs. Emerald vs. Alexandrite |
Ruby: stronger violet absorption, transmits in blue and red - eye more sensitive to red so that is what we see
Emerald: transmission window shifted to blue green and red - eye more sensitive to green so that is what we see
Alexandrite: transmits bluish-green and red light - in sunlight appears mostly green |
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Dispersed Metal Ion Colour - Epidote and Tourmaline |
Epidot: pleochroic colours due to geometric distortion of octahedral at iron site
Tourmaline: blue caused by dispersed Fe2+, but charge transfer between two adjacent iron ions often contributes to green colour |
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Where are most South Sea Pearls from |
Burma |
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Farmers are lucky if they get ___% yield from harvested oysters |
20 |
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Natural Pearl |
6-spot hexagonal x-ray diffraction pattern (obtained in any direction)
x-ray diffraction patterns obtained with cultured nucleated pearl - 6-spot: perpendicular to m-o-p layers - 4-spot: in line with layers |
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Methods used by testers to determine type and composition of pearl |
1. X-Ray Fluor: freshwater vs. seawater 2. Candling: determine thickness of nacre 3. Lauegram: identify presence of nucleus 4. Microsection: examine structural profile |
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Black Pearl Facts |
Not available before 1970s Took hold in French Polynesia Shell of P. margarifitera - treasured by Polynesians |
