EES 1030 Study Guide - Midterm Guide: Silicate Minerals, Lava Dome, Spheroidal Weathering
18 Mar 2016
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Definition: ordered internal structure, specific chemical composition, naturally occurring, inorganic solid. Polymorphs: minerals with same composition but different crystalline structures. Igneous rocks: (dark, mafic silicates: olivine, pyroxene, amphibole, and biotite mica. Compositions ^: light silicates, felsic, continental crust. Granite(plutonic) & rhyolite(volcanic: dark, mafic, oceanic crust. 3: ultramafic, earth"s mantle- (olivine & pyroxene) Intrusive/plutonic- deep in magma, over 80% of magma produced never reaches the. Intrusion types: shape: tabular (sheetlike) vs massive. Orientation with respect to the host (surrounding) rock: dike: discordant, cut across the layers in country rock, sill: concordant, parallel to the layers in country rock. Classified based on texture, types of minerals and chemical composition. Textures: (slower cooling = larger crystals: aphanitic: ( < 1mm) fine grained rock. Rapid rate of cooling near the surface: phaneritic: large visible crystals (1-20mm). Slow rate of cooling: poryphritic: large crystals (phenocrysts) are embedded in a matrix of smaller crystals (ground mass). Minerals form at different temperatures: pegmatic: extremely coarse grained rock.
