Term
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Definition
| Crystals larger than 1cm; slow cooling magma |
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Term
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Definition
| Crystals about 1-10mm; slow cooling magma |
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Term
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Definition
| Large and small crystals; change in rate of magma cooling |
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Term
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Definition
| crystals too small to identify, even with a hand lens; rapid cooling of lava |
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Term
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Definition
| Rapid cooling and poor nucleation; ex. Obsedian |
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Term
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Definition
| Like meringue or kind of bubbly; rapid cooling of gas charged lava |
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Term
| Pyroclastic or Fragmental |
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Definition
| Particles emitted form volcanoes |
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Term
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Definition
| Hard, transparent, gray, crystals with no cleavage |
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Term
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Definition
| Hard, opaque, usually pale gray to white crystals with cleavage, often striated |
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Term
| Potassium Feldspar (K-Spar) |
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Definition
| Hard, opaque, usually pastel orange, pink, or white crystals |
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Term
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Definition
| Flat, pale brown, yellow, or colorless crystals that scratch easily and break into sheets |
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Term
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Definition
| Flat, glossy black crystals that scratch easily and break into sheets |
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Term
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Definition
| Hard, dark gray to black, brittle crystals with two cleavages that intersect at 56 and 124 degrees |
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Term
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Definition
| Hard, dark green to green-gray crystals with two cleavages that intersect at nearly right angles |
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Term
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Definition
| Hard, transparent to opaque, pale yellow-green to dark green crystals with no cleavages |
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Term
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Definition
| Shows the percentage of a rock's green, dark gray, and black mineral crystals. |
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Term
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Definition
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Term
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Definition
| Very flat foliation developed along flat, parallel, closely spaced, shear planes |
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Term
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Definition
| Wavy and/or wrinkled foliation of fine-grained platy minerals that gives the rock a satiny or metallic luster. |
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Term
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Definition
| A scaly, glittery, layering of visible platy minerals and/or linear alignment of long prismatic crystals. |
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Term
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Definition
| A medium to coarse grained aggregate of inter-grown, usually equal sized, visible crystals. Ex. Marble |
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Term
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Definition
| A fine-grained aggregate of inter-grown microscopic crystals. Ex. Hornfels |
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Term
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Definition
| A medium to coarse grained aggregate of fused, sand sized grains that resemble sandstone. Ex. Quartzite |
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Term
| Glassy Texture (metamorphic) |
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Definition
| A homogeneous texture with no visible grains or other structures and breaks along glossy surfaces. Ex. Anthracite Coal |
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