Rocks - Rocks 18:22 Igneous Meansfireformed...

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Rocks 18:22 Igneous Means fire formed Crystallized from hot molten magma or lava as its cooled Magma=beneath surface o Intrusive rocks Intrusive or plutonic igneous rocks for from magma which cooled  beneath the surface of the earth Coarse grains because takes long to cool- phanaritic Slow cooling=coarse grained Ex: granite, gabbro, diorite Lava=above surface o Extrusive Rocks Volcanic rocks for from lava which cooled on the earth’s surface Usually finer grain rocks because they cool fast-aphinitic Quick cooling=fine grained Ex: Basalt, rhyolite, andesite, obsidian Cooling history and grain size The texture of a rock is a description of its grain size Cooling rates influence the texture of the igneous rock Lava cools much more quickly than magma because lava is on the surface of  the earth, where temperatures are much lower than they are at depth. Composition groups for igneous rock
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1. Sialic rock  2. Intermediate rock (has some light and dark minerals) 3. Mafic (has magnesium and iron minerals, dark and dense rock) 4. Ultramafic (darkest, most dense rock) Sialic Rocks Silica-rich rocks Light colored Has light colored minerals such as quartz and potassium feldspar
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Rocks - Rocks 18:22 Igneous Meansfireformed...

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