Rocks and Minerals Science 2201 Grains of sand… Many ongoing processes constantly change the surface of the globe Our Earth is cyclic and restless In other words, -everything on the earth operates in cycles -the surface of the earth is constantly changing Geology • The science that considers the history of the earth, as recorded in rocks Basic Structure of the Earth • 8,000 miles in diameter • lithosphere, hydrosphere, atmosphere • spherical regions: – crust, mantle, outer core, inner core Earth Structure Rocks • Igneous = formed by the cooling and crystallization of magma (melted rock) • Sedimentary = formed from accumulation of weathered material (sediments) • Metamorphic = formed from preexisting rocks that have been transformed (changed) Igneous, Sedimentary, Metamorphic  Each type of rock records a different complex past  Each type of rock can be changed from one form to another and back again  geologists call these transformations the “rock cycle” Physical Properties of Minerals • Crystal form • Hardness • Plane of Cleavage • Luster • Color and Streak • Specific Gravity Mineral Luster • the appearance of its surface as it reflects light • minerals of the same color can have different luster Color and Streak • Color: red rubies, or blue sapphires, same mineral—corundum (Al2O3) • Streak refers to the color of a mineral in its powdered form, example – hematite Specific Gravity • A density measure • compares weight of a volume of substance to the weight of the same volume of water • Example: – cm3 pyrite weighs 5X as much as cm3 water – cm3 gold weighs 20X more than cm3 water Igneous Rock • formed by cooling & crystallization of magma • means “formed by fire” • make up about 95% of the earth’s crust • basalt (ocean floor) and granite (continents) are common examples Igneous Rock • Extrusive • Form at earth surface Example-basalt Fine texture Small minerals Fast cooling • Intrusive • Form inside crust Example-granite Course texture Large minerals Slow cooling Igneous Rocks Texture Silica Content High Medium Low Course Granite Diorite Gabbro Fine Rhyolite Andesite Basalt Glassy Obsidian Basalt (gl) Vesicular Pumice Scoria Sedimentary Rock • formed from the weathered material carried by water, wind, or ice • most common rocks in the upper crust • cover over 2/3 of the earth’s surface • sandstone, shale, and limestone Sedimentary Rock • Clastic • Broken pieces of rock • Particle deposition at river bottom, beach, or desert • Cementation • Ex-quartz mineral forms sandstone • Chemical • Dissolved materials precipitate from solution • Inorganic or organic • Ex-calcite mineral or calcium carbonate from shells forms limestone Sedimentary Rocks Sediment Sedimentary Rock Gravel and cobbles Conglomerate Sand Sandstone Silt and clay Shale Calcium carbonate Limestone Calcium sulfate Gypsum Sodium chloride Halite Metamorphic Rock • -formed from preexisting rocks (igneous, sedimentary, or other metamorphic) • metamorphic means “changing in form” • marble and slate are common examples Metamorphic Rock • Foliated • Elongated minerals align in parallel layers • H & P separates minerals into parallel layers • Igneous granite to metamorphic gneiss • Nonfoliated • Smooth, solid homogenous blend of minerals in rock • H & P recrystallizes rock • Igneous limestone to metamorphic marble Metamorphic Rock Original Rock Metamorphic Rock Sandstone Quartzite Limestone Marble Shale Slate, Schist Granite Gneiss Metamorphic Rock Origin • Slate • Quartzite • Marble from shale from sandstone from limestone Discussion Question for Review • Chapter 17 Try p 362-363 Discussion Questions 1-5, 7,9,10 • Chapter 18 Try p 387 Discussion Questions 1,2,3,5 [...]... Cycle What are Rocks? What are Minerals? • Rocks • Minerals • An aggregate or mixture of minerals • Composition can vary • Most rocks are composed of more than one mineral • Inorganic chemical elements or compounds found in the Earth’s crust • > 3000 minerals are found in Earth’s crust Limestone made of Calcite Granite contains 3 minerals Minerals • minerals are the building blocks of rocks • differ... Sedimentary Rocks Sediment Sedimentary Rock Gravel and cobbles Conglomerate Sand Sandstone Silt and clay Shale Calcium carbonate Limestone Calcium sulfate Gypsum Sodium chloride Halite Metamorphic Rock • -formed from preexisting rocks (igneous, sedimentary, or other metamorphic) • metamorphic means “changing in form” • marble and slate are common examples Metamorphic Rock • Foliated • Elongated minerals. .. earth’s crust • basalt (ocean floor) and granite (continents) are common examples Igneous Rock • Extrusive • Form at earth surface Example-basalt Fine texture Small minerals Fast cooling • Intrusive • Form inside crust Example-granite Course texture Large minerals Slow cooling Igneous Rocks Texture Silica Content High Medium Low Course Granite Diorite Gabbro Fine Rhyolite Andesite Basalt Glassy Obsidian... formed from the weathered material carried by water, wind, or ice • most common rocks in the upper crust • cover over 2/3 of the earth’s surface • sandstone, shale, and limestone Sedimentary Rock • Clastic • Broken pieces of rock • Particle deposition at river bottom, beach, or desert • Cementation • Ex-quartz mineral forms sandstone • Chemical • Dissolved materials precipitate from solution • Inorganic... composition and properties See Minerals link on Pacing Guide • Weinman Mineral Museum…you gotta go! Crystal Form • Pyrite, Fe2S • Quartz, SiO2 Moh’s Hardness Scale • • • • • 1.Talc 2.Gypsum 3.Clacite 4.Fluorite 5.Apatite • 6.Orthoclase • 7.Quartz • 8.Topaz • 9.Corundum • 10.Diamond Cleavage & Fracture Physical Properties of Minerals • Crystal form • Hardness • Plane of Cleavage • Luster • Color and Streak... separates minerals into parallel layers • Igneous granite to metamorphic gneiss • Nonfoliated • Smooth, solid homogenous blend of minerals in rock • H & P recrystallizes rock • Igneous limestone to metamorphic marble Metamorphic Rock Original Rock Metamorphic Rock Sandstone Quartzite Limestone Marble Shale Slate, Schist Granite Gneiss Metamorphic Rock Origin • Slate • Quartzite • Marble from shale from sandstone... Minerals • Crystal form • Hardness • Plane of Cleavage • Luster • Color and Streak • Specific Gravity Mineral Luster • the appearance of its surface as it reflects light • minerals of the same color can have different luster Color and Streak • Color: red rubies, or blue sapphires, same mineral—corundum (Al2O3) • Streak refers to the color of a mineral in its powdered form, example – hematite Specific