IgRocks - Chapter 3, Igneous Rocks Magma molten rock; a...

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Chapter 3, Igneous Rocks Magma – molten rock; a silicate melt (a liquid produced from the melting of predominantly silicate minerals) Lava – magma above the Earth’s surface Magma formed by partial melting of a small part of the mantle. A small % of the rock in an area of the mantle melts to form magma. The magma is less dense than the rocks around it so it rises. Partial melting occurs because of: Geothermal gradient Pressure release Introduction of volatiles (materials that will readily vaporize, or form a gas, at surface pressures) such as water Igneous rock – type of rock formed when magma cools and crystallizes Igneous rock may be either intrusive/plutonic extrusive/volcanic Crystallization of magma – process of forming crystals of minerals from the elements in the magma. Solids form as the liquid magma cools. (Opposite of melting, which is when liquid forms as a solid melts.) Rate of crystallization controls size of crystals.
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IgRocks - Chapter 3, Igneous Rocks Magma molten rock; a...

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