Term
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Definition
Isolated tetrahedra
Divalent: olivine
Trivalent: kyanite/andalusite/sillimanite
Di/trivalent: garnet
Tetravalent: zircon |
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Term
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Definition
double tetrahedral groups
ex: melilite |
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Term
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Definition
4 or 6 member rings
ex: beryl, tourmaline |
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Term
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Definition
Chain silicates
Single chain: pyroxene
Double chain: amphibole |
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Definition
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Term
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Definition
framework silicates
ex: quartz, feldspar, zeolite |
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Term
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Definition
(Mg,Fe)2SiO4
End members Fayalite (Fe), Fosterite (Mg) |
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Term
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Definition
| (Ca,Na)2(Mg,Al)(Si,Al)2O7 |
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Term
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Definition
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Term
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Definition
| orthopyroxene, pigeonite, augite, protopyroxene |
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Term
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Definition
| albite, oligoclase, labradorite, anorthite |
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Term
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Definition
| orthoclase, anorthoclase, microline |
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Term
| plagioclase feldspar formula |
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
| (Ca,Na)(Mg,Fe,Al)(Si,Al)2O6 |
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Term
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Definition
| (Ca,Na)₂(Mg,Fe,Al)₅(Al,Si)₈O₂₂(OH)₂ |
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Term
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Definition
Andalusite
-2 directions cleavage, pink pleochroism, high relief, low 1st order interference |
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Term
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Definition
Anorthoclase (alkali feldspar)
-slight signs of cleavage, smooth PPL look, twin cross hatch lamellae- confused with microline |
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Term
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Definition
Apatite
-seen as needles/small hexagons, mod-high relief, roughly same birefringence as nepheline |
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Term
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Definition
Augite (pyroxene)
-up to 2nd order interference colors, no cleavage visible |
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Term
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Definition
Biotite
-brown or green PPL pleochroism, perfect cleavage 1 direction, diagnostic mottling near extinction |
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Term
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Definition
| Clinopyroxene/orthopyroxene intergrowth |
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Term
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Definition
Cordierite
-dusty look in PPL, irregular cracks, veins at edges, low interference, some lamellae twinning, diagnostic yellow halo |
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Term
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Definition
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Term
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Definition
Epidote
-yellow pleochroism, good cleavage, bright interference colors, high relief |
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Term
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Definition
Garnet
-high relief, inclusions common, isotropic |
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Term
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Definition
Hornblende
-green to brown pleochroism, two direction cleavage, up to 2nd order blue |
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Term
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Definition
Kyanite
-high relief, well developed cleavage, low interference colors |
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Term
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Definition
Labradorite (plagioclase feldspar)
-cleavage visible, lamellae (dark and light bands), low order interference |
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Term
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Definition
Leucite
-colorless PPL, can have multiple twinning, low 1st order interference |
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Term
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Definition
Muscovite
-low relief, usually colorless PPL, perfect cleavage 1 direction, diagnostic mottling near extinction |
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Term
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Definition
Nepheline
-no cleavage seen, colorless PPL, low 1st order interference colors, commonly seen w/alkali feldspar |
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Term
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Definition
| Nepheline-Pyroxene intergrowth |
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Term
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Definition
Olivine
-irregular cracks w/slight alteration, high birefringence |
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Term
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Definition
Orthopyroxene
-green to pink pleochroism, high relief, fairly low interference colors |
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Term
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Definition
Quartz (metamorphic rock)
-no twinning or cleavage, clear in PPL |
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Term
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Definition
Quartz (volcanic rock)
-generally unaltered, white/yellow interference color, no twinning or cleavage |
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Term
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Definition
Serpentine
-pale yellow PPL, perfect basal cleavage, low 1st order colors, diagnostic mesh texture |
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Term
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Definition
Sillimanite
-high relief, high interference colors cut along prismatic crystal, can be needle like |
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Term
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Definition
Staurolite
-yellow pleochroism, high relief, black edges, low interference |
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Term
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Definition
Talc
-second order (pastel) colors |
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Term
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Definition
Topaz
-mod relief, perfect cleavage, white veins of musc common on edges, low interference colors |
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Term
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Definition
Zircon
-high relief, good cleavage, high interference colors |
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Definition
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Definition
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Definition
Calcite
-good visible cleavage, high order interference pastel color and white, twinning |
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Term
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Definition
Chlorite
-pale green PPL, pleochroism, perfect cleavage, anomalous interference colors (grey, blue, yellow) |
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Definition
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Definition
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Term
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Definition
Microline
-low order interference colors, texture veiny or cross hatched twinning |
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Term
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Definition
Rutile
-cleavage 2 directions, deep golden brown color, twinning evident near extinction |
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Definition
Tourmaline
-high relief, pleochroism, wide range of colors, thin marks perp to crystal edge |
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