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Igneous Rocks By: Kyla Clairray Cortez

What are Igneous Rocks? Igneous rock is one of the three rock types. Formed when magma cools and hardens. When lava cools very quickly, no crystals form and the rock looks shiny and glasslike.

Two Main types based on origin Intrusive Granite Gabbaro Diorite Dunite

Extrusive Rhyolite Andesite Basalt

Based on Texture Fine-grained texture Vesicular texture Coarse-grained texture Porphyritic texture Glassy texture

Chemical Composition Reflects the composition of the magma Magma determines the minerals set of hypothetical minerals - crystallize from magma can vary continuously cannot be easily determined in the field

Dominant Minerals Minerals: Chemical compostition of the magma The inadequacy of a mineralogical classification based on minerals present if you look at the classification schemes for volcanic rocks

Color Color of a rock depends on the minerals present and on their grain size. Feldspar and quartz - light colored Pyroxenes, olivines, and amphiboles (ferromagnesium minerals) - dark colored.

References tm igneous-rocks-textures-and-composition.html m

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