Rocks and Minerals GEO 155 October 30th Mineral Naturally occurring inorganic homogeneous solid with consistent usually chemical composition and a definite consistent atomic structure Can be single element or compounds Over 4000 known species Examples Quartz Calcite Halite Gold silver Which of these is a mineral Minerals Interestingly water is not a mineral but Is a snowflake Sea ice YES How why Naturally occurring Inorganic solid Definite chemical composition Ordered internal structure 2010 United States Mineral Commodity Consumption Mineral Commodity Millions of Metric Tons Crushed Stone 1 200 0 Sand and Gravel 786 1 Salt 55 8 Iron Ore 48 0 Phosphate Rock 30 5 Gypsum 22 5 Clays 21 3 Dimension Stone 14 0 Lime 18 5 Sulfur 11 30 Bauxite 8 4 Potash 5 6 Soda Ash 5 2 Barite 2 66 Copper 1 74 Lead 1 40 Values above are estimates of mineral commodity consumption from the United States Geological Survey Many other commodities could be added to this table Uses of Minerals What are the top two consumptions of minerals used for Why is salt so high The city of Syracuse s salt budget is 45 000 tons each winter Mineralogy Minerals can be described by among other things Crystal structure Hardness Luster Magnetism Color Streak Cleavage http www minerals net Minerals A aspx Rocks Solid mass composed of one or more minerals There are three basic types of rocks Igneous Metamorphoric Sedimentary Igneous Formed by the solidification cooling of molten rock material As it cools it hardens into individual mineral crystals which interlock to form solid rock Rate of cooling affects the properties of the rock Extrusive igneous Intrusive igneous Extrusive Form above the earth s surface Form when molten material is erupted out at the earth s surface and cooled rapidly Little time for large crystals to grow Made up of lots of tiny microscopic crystals Extrusive Basalt Scoria Obsidian Pumice Andesite Rhyolite Intrusive Formed beneath the earth s surface Cool slower than extrusive rocks Time for large but relatively few crystals to form Typically have large crystals seen with the naked eye Intrusive Diorite Peridotite Gabbro Granite Pegmatite Metamorphic Form when pre existing rocks are subjected to high extremes in temperature and pressure Forces can be great enough to actually change the mineral content by changing atomic arrangement Metamorphic New rocks classified based on Initial rock from which they formed Metamorphosed limestone marble Degree of metamorphism Progressively greater metamorphism of shale may create slate schist or gneiss Two main types Foliated have layered or banded appearance that is produced by exposure to heat and directed pressure Non foliated do not have a layered or banded appearance Metamorphic Rocks Slate Novaculite Phyllite Schist Marble Soapstone Gneiss Sedimentary Form from the remains of older rocks Rocks are weathered broken down and the particles created may be transported Particulates accumulate somewhere e g bottom of ocean Lower layers become compacted and cemented together over time forming new rock Sedimentary Easy to identify by the layering process Often find alternating layers of different kinds of sedimentary rocks Layers reflect the environment of the time Common in Central New York once covered by oceans Three types Clastic Chemically precipitated Organic sedimentary rocks Clastic Form from broken rock and mineral fragments cemented together Classified by the size of the particles that have been cemented together Sand sized particles sandstone Clay size shale Clastic Conglomerate Shale Breccia Siltstone Sandstone Chemically Precipitated Form when dissolved materials in water precipitate out to form a new solid Classified by their composition Calcite limestone Chemically Precipitated Limestone Iron Ore Rock Salt Dolomite Chert Organic Form from the accumulation of plant or animal debris Fossils generally are found only in sedimentary rocks Organic Coal Flint Oil Shale In Summary