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flattened layers that sparkle usually light white/silver or dark black/green schist. Nonfoliated: rocks are heat altered, or chem. reaction crystal edges.
Typology: Slides
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Rock type Classification (how formed)
Identifying features (^) Rock Name grain size colors Igneous Intrusive : cools slower underground, crystals big enough to see
crystals bigger than small sand grains
black/white or pink/black/white
granite
black/white diorite
Extrusive: cools quickly above ground, crystals too small to see
crystals too small to see & gas bubble holes
usually black but can be reddish if oxides
scoria
no crystals usually black obsidian Sedimentary Clastic: sediment grains pressed or rock fragments cemented back together
small individual grains
white, tan or reddish
sandstone
very small grains, can’t see them
dark gray to black shale
large and small rounded grains
various individual grain colors
conglomerate
Chemical: dissolved minerals precipitate out of water
very small, usually can’t see grains
usually white or tan limestone
Metamorphic Foliated: rocks become layered due to high heat and pressure
very small, thin layers
light gray or black slate
very small with thicker layers
alternating layers with different colors
gneiss (nice)
flattened layers that sparkle
usually light white/silver or dark black/green
schist
Nonfoliated: rocks are heat altered, or chem. reaction
crystal edges blend together, usually don’t see individual crystals
white color or pink/purple
quartzite