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Rocks
Earth and Environmental Science
Question | Answer |
---|---|
Igneous rock | rock that forms when magma cools and solidifies |
Porphyritic | igneous rock that has a mixture of large and small crystals (ex: granite) |
Vesicular | igneous rock that has holes produced from gas bubbles trapped during the cooling process. (ex: pumice) |
Felsic | describes magma or igneous rock that is rich in feldspars and silica and that is generally light in color. |
Mafic | describes magma or igneous rock that is rich in magnesium and iron and that is generally dark in color. |
Intrusive | intrusive igneous rock has cooled slowly inside the ground, and has large crystals |
Extrusive | extrusive igneous rock cooled quickly above ground, and has a texture with small crystals or no visible crystals. |
Granite | intrusive, large crystals, usually pink, gray, black, white |
Obsidian | dark colored volcanic glass |
Basalt | extrusive, black rock, not shiny |
Pumice | extrusive, usually gray, lots of vesicles, floats |
Sedimentary rock | rocks created from sediment. Determined by the source of the sediment, the way the sediment was moved, and the conditions under which it was deposited. |
Compaction | the process in which the volume and porosity of the sediment is decreased by the weight of the overlying sediments. |
Cementation | the process in which minerals precipitate into pore spaces between sediment grains and bind sediments together to form rock. |
Chemical sedimentary rocks | sedimentary rock that forms when minerals precipitate from a solution or settle from a suspension. (ex: halite and gypsum) |
Organic sedimentary rocks | sedimentary rock that forms from the remains of plants or animals. (ex: coal and limestone) |
Clastic sedimentary rocks | sedimentary rock that forms when fragments of preexisting rocks are compacted and cemented together. (ex: shale, sandstone, conglomerate, breccia) |
Sorting: | the tendency for currents of air or water to separate sediments according to size. Sediment becomes well sorted after being transported a greater distance. |
Angularity | how jagged or smooth the edges of a rock or sediment particle are. When a rock fragment first breaks off of a larger rock, it is very jagged or angular. After it has been transported by wind or water, the fragment becomes less angular and more rounded. |
Limestone: | organic, usually white-gray, often contains fossils, reacts with acid |
Shale: | clastic, made of silt/mud, usually black, thin pieces |
Sandstone: | clastic, made of sand, usually light in color |
Conglomerate (ex. Pudding stone): | clastic, made of rounded pebbles embedded in a silt/sand matrix |
Contact metamorphism | a change in the texture, structure, or chemical composition of a rock due to contact with magma. |
Regional metamorphism | a change in the texture, structure, or chemical composition of a rock due to changes in temperature and pressure over a large area, generally as a result of tectonic forces. |
Foliated: | metamorphic rock texture in which mineral grains are arranged in planes or bands. |
Non-foliated | metamorphic rock texture in which mineral grains are not arranged in planes or bands. |
Slate: | foliated, black, metamorphic version of shale. |
Schist: | foliated, looks like a triscuit cracker, light colors |
Gneiss: | foliated, black and white bands |
Marble | non-foliated, usually white or gray, reacts with acid, metamorphic version of limestone. |