Geology ed

free textbook at https://opengeology.org/textbook/

Minerals ed

composition

• felsic: (feldspar, high Si) low density, lower melting temp, brighter, closer to the surface
• intermediate
• mafic: lower Si, more Mg, Fe,.... mantle, pyroxene, olivene
• ultramafic:

igneous

• extrusive: quickly to the surface, fine grained
• intrusive/plutonic: cooling slowly below surface, coarse grained

texture

• phaneritic: large grains, intrusive
• aphanitic: very fine grained, glass like
• pegmatitic: very large grains/crystals
• porphyritic: fine grained with large chunks (phenocrysts), multistage cooling
• vesicular: bubbles from dissolved volatiles
• pumice: extreme vesicular, floats on water

examples

• olivine: (Fe,Mg)_2 Si O_4, making most of the mantle, ultramafic
• basalt: mafic, extrusive, ocean ridge
• granite: felsic, intrusive
• rhyoliye: felsic, extrusive, pinkish, quartz phenocrysts
• obsidian: felsic, aphanitic

Volcanoes ed