Earth Sciences 1022a Lecture Brief 18 Sep 09MINERALSMinerals are solid chemical compounds that combine to form rocks. They are found in nature and vary in atomic bonding, molecular structure, and element composition, all of which determine their chemical, physical properties and permit their identification.- an infinite number of chemical combinations are possible and almost 4000 natural minerals are known; however, only about 20 minerals dominate the Earth's crustCommon Minerals:natural solid compounds found commonly in Earth's crustSilicates- most abundant; made of the silicon-oxygen tetrahedron(silica, (SiO4)-4) bonded to various metallic cationsferromagnesian (dark) silicates: contain Fe+2and Mg+2cationsolivine - covalently-bonded silica tetrahedra surrounded by Fe, Mg cations; Fe, Mg substitutefor each other to form a familyof minerals; pyroxene- single chainsof tetrahedra ionically bonded to metallic cations, nearly right angle cleavage; amphibole - double chains
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Minerals Minerals, perfect platy cleavage, crust Common Minerals