ESC-1000 Chapter Notes - Chapter 2: Silicate Minerals, Feldspar, Plagioclase
17 Nov 2017
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Igneous: when molten rock solidifies, any rock can be transformed from all 3 types into a different type. 2. 2 igneous rocks: molten rock is called magma if it is i(cid:374)side of earth"s surface, molten rock is called lava if it has erupted from the surface. Lava consists of volatile gases such as water vapor and contains mineral crystals. If magma cools but moves upward it can have multiple stages of cooling resulting in a porphyritic texture: n. l. Bowen discovered that when magma cools, minerals will crystalize in a specific order: dark silicates (olivine) are first with highest temperatures of crystallization, light silicates (quartz) crystalize at lowest temperatures. Igneous rocks are classified in groups based on their % of dark or light silicate minerals that they contain: granitic, granite and rhyolite. Light silicate minerals such as potassium feldspar: andesitic, plagioclase feldspar and amphibole, basaltic (mafic, basalt, pyroxene.
