GEOG 1290 Lecture Notes - Lecture 12: Mineral Alteration, Clastic Rock, Feldspar
24 Oct 2017
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Slide 4 - the earth"s crust and composition. Crust = thin, outermost layer of the earth q ranges from 8-40 km thick q 75% of crust composed of oxygen and silicon. Metallic elements account for the remaining majority q aluminum - 8% q iron - 5% Mineral - naturally occurring inorganic substance q e. g. , quartz. Rocks - composed of minerals q great variety (characteristics, compositions and ages) q e. g. , granite, limestone, marble. Three major classes of rock: q igneous, sedimentary and metamorphic rocks. Sedimentary - from debris eroded from other rocks and other materials. Metamorphic - rocks changed by heat and / or pressure. Constantly transforming from one type to another. Silicate minerals - compounds of silicon and oxygen. Felsic minerals (feldspar & silica): q e. g. , quartz, feldspars q light in color and low density. Mafic minerals (magnesium & iron (fe)): q e. g. , mica, amphibole, pyroxene q dark and color and more dense.
