Study ES 108 Final Flash Cards

 
Pile Management Card
ES 108 Final

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Dispersion
-separation of white light into a rainbow of colors
color center
structural imperfections in cyrstals causing selective absorption of light.
Boule
-synthetic crystal formed by flame fusion
Adamanitine
-diamond like luster
Dates to Know
•1725 – diamonds discovered in New World
•1792 – French Revolution, Hope Diamond stolen
•1812 – Hope Diamond (French Blue) resurfaces and is sold; after 20 years an object stolen from France is no longer France’s property.
•1859 – diamonds first discovered in South Africa
Hexagonal System
Crystal System of:
-Corundum
-Tourmaline
-Quartz
Amorphous
-a class of gems that does not have a crystalline structure

(ex: glass, amber, opal)
labradorescence
phenomena - mettalic hues on gemstone (mainly labradorite)
adularescence
phenomena -
blue/white inclusions that glow; present in moonstones
chatoyancy
phenomena -
cat's eye
opalescence
phenomena -
light diffraction in opal
orient
phenomena -
rainbow-like colors in pearls
Monoclinic Crystal System
Crystal System of:
-Jade
Orthorhombic System
Crystal System of:
-Pearl
-Chrysoberyl
-Olivine
Hexagonal System
w/
Ring Silicates
Crystal Sytem of:
-Beryl
Cubic System
Diamonds' Crystal System
Garnet's Crystal System
Biomineralization
the formation of a gem-mineral by a living organism
Fancy Gems
-"colored gems"
Zircon
-Type of gem
-Streak: White
-Crystals: Tetragonal -Luster: resinous to adamantine
-Doubly Refractive - causing obvious doubling of facets
-Contains Uranium & Thorium - which undergo radioactive decay
Jade
-"Green"; ornamental stone valued for centuries in the Orient
-"thought to bring good luck"
Ionic Bond
-Weak type of chemical bond
Diamond
-Polymorph of Carbon
-Luster: Adamantine
-“diamante” or “adamas” – means “invincible”
-form at core-mantle boundary (high pressure, high temperature conditions); found in kimberlite
-10 on hardness scale
Olivine
-named for greenish color; due to iron
-periodot
hardness - 6.5 colors, yellow, olive green
Garnet
-"granatus" - Latin, grain in allusion to its appearance in the matrix, like seeds in a pomegranite
* "Singly Refractive"
-Luster: vitreous (adamantine in demantoid)
Pyroxene
-Type of rock-forming mineral
-Single Chain
-Jade
Coral
•Origin – skeletons of marine corals; tropical seas
•Composition – aragonite
•Hardness: 3-4
•Colors – various
•Streak – white
•Luster – vitreous (when polished)
•Fluorescence – weak, violet.
3 Types of Industrial Diamonds
-what type of diamonds?
- bort - poorly crystalized
- ballas - spherical, small
- carbonado - meteorite diamonds
Central Selling Org. (CSO)
-group of diamond producers that cooperatively sell diamonds
-controls 60-80% of world’s diamond legal trade
Cecil Rhodes
– S. Africa, 1870; bought claim in Da Beers mine
-Formed Da Beers Mining Co. Ltd.
-Limited sales of diamonds to stabilize prices
-1890; Elected prime minister of S. Africa
Idiochromatic
– “self-colored,” color-causing elements are essential to chemical composition of stone (ex: Corundum – ruby)
Allochromatic
- "colored,” gems colorless when pure; color produced by impurities
Pleochroism
-color change of minerals at different angles
Streak
-color of a powdered mineral
Fracture vs. Cleavage
Fracture - breakage on surface
Cleavage - breakage on weak planes
Polymorphs
-having the same chemical compositions but diff. crystal structure (diamonds and graphite)
Van der Waals Bond
-weakest bond
-present on cleavage planes
Covalent Bond
-strongest type of chemical bond
Phosphorescence
- energy absorbed by a substance is released; “glow-in-the-dark”
Fluorescence
– glow exuded by diamonds or other gemstones when exposed to ultraviolet light
Crystal
-a solid having a regular internal arrangement of atoms or ions, with flat surfaces
Metamorphic Environments
-gemstone environment
-rocks changed by heat/pressure
Igneous Environments
-gemstone environment
-magma/molten rocks
4 C's
-Cut – ideal proportions for a gem; optimize brilliance and fire to increase value of gem
-Color – some colors more desirable than others (blue = most desirable)
-Clarity – flaws decrease value (cracks, inclusions)
-Carat Weight – larger stone = greater value
Stability
-resistance to color loss due to heat, light or chemicals
Toughness
-resistance to chipping/fracturing
Moh's Hardness Scale
-1 – Talc
-2 – Gypsum
-3 – Calcite
-4 – Fluorite
-5 – Apatite
-6 – Feldspar/Orthoclase
-7 – Quartz
-8 – Topaz
-9 – Corundum (Sapphires)
-10 – Diamond (Carbon)
Durability/Hardness
-resistance to scratching
Critical Angle
-angle at which total internal reflection is achieved
Refraction
-bending of light as it passes from air to gem
Reflection
- bouncing of light off a facet
5 Facets of a Gemstone
-Table – top facet, largest, flat surface on top of stone
-Crown – top of stone (upside down it looks like a crown)
-Girdle – edge between crown and pavillon
-Pavillon – lower part of stone
-Culet – small facet on bottom of stone, made to decrease likelihood of fracture when dropped
Facet
-a flat, polished surface of a gemstone
Luster
-appearance of light as it reflects off the surface of a gem.
Fire
-rainbow-like flashes of color in gems
Brilliance
-amt of sparkle a gemstone has
Beauty
key attribute of a gemstone
Gem
-material that is sufficiently durable and attractive to be used for personal adornment
Ammolite
oAragonite shell of cretaceous ammonite cephalopods
Relatives of the modern nautilus
Shell still has mother of pearl layer
Fossil
-evidence of ancient life; at least 11,800 yrs old
Jet
•Origin: bituminous coal; sedimentary deposits, worldwide, mostly from England.
•Origin of name: from old French, jaiet
•Composition: carbon
•Streak – black
Coral
•Origin – skeletons of marine corals; tropical seas
•Composition – aragonite
•Hardness: 3-4
•Colors – various
•Streak – white
•Luster – vitreous (when polished)
•Fluorescence – weak, violet.
Shell
•Origin – Aqueous mollusks
•Composition – calcium carbonate – CaCO3
•Hardness: 2.5-3.5
•Colors – various
•Streak – white
•Luster – dull, vitreous, pearly
2 Types of Amber
1) Amber - Fossil Resin - millions of years old
2) Copal - Subfossil resin - thousands of years old
Terpenes
-organic chemicals in resins that give conifer trees aroma (which become linked as resin hardens)
Amber
-• From Latin, ambrum, after Arabic, anbar, meaning amber.
•Hardened tree resin (in sedimentary deposits)
-Wound is seals off by resin
-Before hardening a resin may trap bubbles, insects, etc.
•Composition: mix of organic resins
•Hardness: 2-2.5
•Colors: mostly yellow, brown, sometimes greenish
•Streak: white
•RI: 1.54 – amorphous compound
•Luster: Vitreous to resinous (polished)
•Fluorescence: bluish-white to yellow-green. Inclusions are common
”essence d’orient”
-pearl simulate - made from fish scales for shininess
Cultured Pearls
•Pearls produced by oysters through the intervention of humans
Baroque Pearls
-pearls having unusual shapes
Nacre
-"mother of pearl", an organic-inorganic material produced by some mollusks as an inner shell layer; it is also what makes up pearls.
Pearls
-Origin of name – probably from Latin, perula, pearl
-Composition: calcium carbonate (CaCO3) + conchiolin (organic binding agent) + water
-Hardness: 2.5-4.5 (usually 3.5)
-Colors: Various
-Luster: pearly, iridescent (“orient”).
-Other: fracture uneven.
-Fluorescence: often pale green or reddish
Gold Plate (GP)
- Vermeil -
-very thin layer of gold electroplated to surface of a base metal, often sterling silver
Precious Metal
-a rare, naturally occurring metallic chemical element of high economic value
Platinum
•A native element; symbol is Pt
•Name: derived from Spanish, platina, silver-like
•Color: whitish steel gray to dark gray
•Hardness: 4-4.5
•SG: 21.46 (pure); 14-19 alloyed
•Other characteristics: native platinum contains up to 28% iron, and is distinctly magnetic
Tarnish
a thin layer that forms from chemicals in the air over copper, brass, silver, aluminum, and other semi-reactive metals as their outermost layer undergoes a chemical reaction.
Silver
•a native element; symbol – Ag
-Symbol from Latin, argentums
•Color – silvery-white (usually)
•Hardness 2.5-3
-SG – 10.1-11.1, variable; develops a gray to black tarnish according to alloy
Pyrite
-"Fools Gold"
-Has similar appearance to gold; distinguished by being harder, and by brownish-black or greenish-black streak
-Brassy mineral disseminated in lapis lazuli
Placer Deposits
-alluvial deposits of precious metals; mainly flakes or nuggets
Gold
•a native element: symbol – Au
-symbol from Latin, aurum
•Color – Gold; usually
•Hardness – 2.5-3
•Streak – Gold-yellow (usually)
•SG – 19.3 (pure), decreasing w/ alloys
-Crystals in Cubic System
Alloying
-mixing of one or more metals.
Zoisite
-named after Baron von Zois
-strongly pleochroic
-crystals contain oil (hydro-carbon rich fluids)
-heat treated to remove tint and deepen blue color
Tourmaline
-"turmali" - stone w/ mixed colors
Feldspar
-"feld" - field
-"splaten" - to split
2 Types of Jade
Jadeite - pyroxene (single-chain jade)
Nephrite - amphibole (double-chain jade)
Amphibole
-Type of rock-forming mineral
-Double Chain
Metamict
-Crystalline minerals that lose their crystal structure due to radioactive destruction
Curie
-the amount of radioactivity in 1g of radium
Isotropic Age Dating
-way to determine gems age
-done through color and amount of damage they've undergone from radioactive decay
Topaz
-gem named after the Island of Topazos in the Red Sea
-crystals – orthorhombic -Luster – vitreous -streak - white
-pleochroism – yellow or pink

-formed as fluorine bearing vapors are given off in the last stages of solidification of igneous rocks
-occurs in cavities in rhyolite and granite (especially pegmatites)
Assembled Stone
– 2 diff. stones put together
–also known as a - doublet
Obsidian
-origin name, obsius, Roman
-hardness 5.5 -colors - black, brown, green, gray
-arrowheads
3 Types of Opal
-Precious Opal - distinctive play of colors
-Fine Opal - yellow-red/orange color, no play of colors
-Common Opal - opaque, rarely translucent, no play of colors
Opal
-type of gem
-sanskirt, "opala"
-amorphous silicate mineral
-play of colors
Tiger's Eye Quartz
-type of chatoyancy in quartz
-gold-yellow, gold-brown
Flint
-fine grained quartz
-often found in Ohio creek beds
Chalcedony
-type of quartz
-banded, all colors
*petrified wood, bloodstone, jasper, carnelian, onyx
Quartz
-mineral breaks by fracture
-hexagonal crystals
-RI-1.54-1.55
*amethyst
*citrine
*chalcedony -
*carnelian
Spinel
-often mistaken as Ruby
-*octahedron crystals– double pyramid crystal form
Chrysoberyl
-Crystals – orthorhombic
-Colors – yellow, yellow-green, brownish, red, light blue
RI – 1.75-1.76
*alexandrite – extreme pleochrosim – color change in diff. lights; named after Czar Alexander II
*cymophane – “cat’s eye”, cymos, waving…phanos, light.
Topaz
- named after the Island of Topazos in the Red Sea
crystals –orthorhombic -Luster – vitreous
-pleochroism – yellow or pink
Emerald Cut (Step Cut)
- type of gem cut
-developed because emeralds are brittle and prone to cracking when bumped.
Beryl
-"green stones" -Hexagonal Crystals
-Ring Silicates
-Aquamarine
-Emerald
-Heliodor
-Morganite
-Goshenite
Asterism- Star Sapphires
-star effect
-axes of star represent - Faith, Hope, Destiny
-travelers wore these to ward off harm
Famous Corundum
*Star of Bombay – blue sapphire, owned by movie star Mary Pickford
*Delong Star Ruby – red ruby, stolen for ransom in 1964 for $25,000
*Star of India – light blue star sapphire, donated to Smithsonian by JP Morgan
*Star of Asia –
*Carmen Lucia Ruby – 23 carat ruby set in a platinum ring owned by Peter Buck
Diffusion Treatment
-type of stone treatment
-color causing impurity added to the surface of a gem. Then heat.
Heat Treatment
-type of stone treatment
-causes changes in oxidation states of impurities; diffuses/spreads out impurities and color.
Verneuil Process
*also knwon as flame fusion
*a way of producing synthetic corundum (rubies and sapphires
Inclusion
- mineral, gas or fluid w/in a crystal
Corundum
Ruby – from Latin, ruber, red.
Sapphire – from Latin, sapphirus, blue.
Composition: aluminum oxide, Al2O3 Luster: Vitreous
Harness: 9
Colors: colorless, red, blue... Streak: white
SG: 4
RI: 1.76-1.77
Crystals: hexagonal
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