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26 Cards in this Set
- Front
- Back
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How do geologists classify rocks?
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Geologists classify rocks by MINERAL COMPOSITION (what they are made of), COLOR, and TEXTURE.
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What are "rock-forming minerals?"
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Minerals that make up rocks. There are about 20 of them.
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What gives a rock texture?
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The particles of minerals in the rock give it texture. These particles are called GRAINS.
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What is a rock's origin?
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The way the rock was formed.
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What are the 3 groups that scientists use to classify rocks?
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Igneous
Sedimentary Metamorphic |
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How does IGNEOUS rock form?
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From the cooling of magma or lava.
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How does SEDIMENTARY rock form?
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From small particles of rock or the remains of plants and animals being pressed and cemented together.
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How does METAMORPHIC rock form?
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When rock is changed by heat and pressure.
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How do scientists classify IGNEOUS rocks?
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By origin, texture, and mineral composition (what they are made of).
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What is an EXTRUSIVE IGNEOUS rock?
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Rock that formed from lava that erupted onto Earth's surface. (hint: "ex-" means "outside of")
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What is an example of an EXTRUSIVE IGNEOUS rock?
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Basalt
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What is an INTRUSIVE IGNEOUS rock?
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Igneous rock that formed when magma hardened beneath Earth's surface (hint: "in"=inside)
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What is an example of an INTRUSIVE IGNEOUS rock?
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Granite
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What determines the texture of an igneous rock?
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The size and shape of its mineral crystals.
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Which type of igneous rock has larger crystals?
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Those produced from magma because slow cooling magma forms coarse-grained rocks. (INTRUSIVE IGNEOUS ROCKS).
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Whick type of igneous rock has small crystals?
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Those formed from rapidly cooling lava-EXTRUSIVE IGNEOUS ROCKS.
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What determines an igneous rock's color?
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Its mineral composition.
Low silica=dark rock High silica-light colored rock |
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What is igneous rock used for?
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Building materials (granite)
Cleaning and polishing (pumice) Tools (obsidian) |
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What is sedimentary rock?
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Rocks formed by a sequence of weathering, erosion,deposition, compaction, and cementation.
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What is weathering?
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Freezing, thawing, plant roots, acid, and other forces cause rocks to break up.
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What is erosion?
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Running water, wind, and ice carry away bits of broken up rock.
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What is deposition?
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When sediment or pieces of the rock settle out of the wind or water that carried it.
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What is compaction?
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Pressing the sediment together which causes the layers to squeeze together (think of a trash compactor)
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What is cementation?
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Dissolved minerals crystalize and glue particles of sediment together to form rocks.
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What is metamorphic rock?
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Rock that form form another rock due to heat or pressure or heat and pressure.
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How do scientists classify metamorphic rocks?
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By how the grains are arranged in the rock.
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