Rocks {rock, types} can be igneous, metamorphic, or sedimentary.
Molten minerals from mantle cool and harden at different rates to make rock {igneous rock}|.
Igneous-rock slow cooling makes coarse grain crystals {granite}|.
dark, hard, smooth {diorite}.
Igneous-rock rapid cooling makes fine grain crystals {obsidian}.
Rhyolite {pumice} can form with gas bubbles.
Fine-grained glassy granite {rhyolite} has color bands.
Basalt lava flows have red-brown, porous rocks {scoria} that contain gas bubbles.
Igneous rocks {sialic rock} can be mostly silicon and aluminum. Granite, continental rock, and sediments are sialic.
soft volcanic rock {tufa}.
aerated light volcanic rock {tuff}.
Sand or clay layers can make rock {sedimentary rock}|. Water, wind, or ice makes sand or clay layers. Layers can be clastic rock, crystallize from shallow lakes or seas by evaporation to make sediment, or precipitate to make sediment. Sedimentary rocks can be calcite limestone and calcium-and-magnesium carbonate dolomite. Sedimentary rocks are the only rocks that have no reheating, so they can retain fossil imprints.
Layers can cement together by pressure {clastic rock}.
Sedimentary rocks {conglomerate rock} can come from stones and gravel in hardened clay.
Sedimentary rocks {sandstone}| can come from sand.
Sedimentary rocks {shale}| can come from clay and wood.
Igneous or sedimentary rocks can change to new forms {metamorphic rock}| by heat and pressure deep in Earth.
Metamorphic rocks {breccia} can come from conglomerate.
Metamorphic rocks {diabase} can come from basalt.
Metamorphic rocks {gneiss} can come from granite.
Metamorphic rocks {marble}| can come from limestone or dolomite.
Metamorphic rocks {quartzite} can come from sandstone.
Metamorphic rocks {schist}| can come from shale and basalt.
Metamorphic rocks {slate, rock}| can come from clay or shale.
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Date Modified: 2022.0225