GLG 101 Lecture Notes - Lecture 3: Magma Chamber, Pegmatite, Phanerite
Document Summary
Heat, pressure and water content is what influences the melting of. Gabbro: refers to a large group of dark, often phaneritic, mafic intrusive igneous rocks chemically equivalent to basalt. It forms when molten magma is trapped beneath the earth"s surface and slowly cools into a holocrystalline mass. Granite: is a common type of felsic intrusive igneous rock that is granular and phaneritic in texture. Granites can be predominantly white, pink, or gray in color, depending on their mineralogy. Obsidian: is a naturally occurring volcanic glass formed as an extrusive igneous rock. It is produced when felsic lava extruded from a volcano cools rapidly with minimal crystal growth (5-6, translucent, vitreous) Pumice: called pumicite in its powdered or dust form, is a volcanic rock that consists of highly vesicular rough textured volcanic glass, which may or may not contain crystals. It may have any texture from glassy to aphanitic to porphyritic. The mineral assemblage is usually quartz, sanidine and plagioclase.
