Illustrations
Page [Guadalupe Peak and El Capitan in the Guadalupe Mountains, Culberson County, Texas] 1 [Earth’s outer crust] 2 [Geologic time scale] 3 [Generalized geologic map of Texas] 4-5 [A mineral is made up of chemical elements] 7 [A rock is made up of minerals] 8 [Extrusive igneous rocks form at the earth’s surface] 9 [Intrusive igneous rocks form beneath the earth’s surface] 10 [Soils develop from weathered rock and associated organic material] 11 [Conglomerate from Webb County, Texas] 11 [Precipitated sediments lining a teakettle] 12 [Contact metamorphism] 13 [A scalenohedron] 14 [Barite specimen showing radial form] 15 [Chalcedony showing botryoidal form] 16 [Transparent mineral] 16 [Streak plate] 17 [Conchoidal fracture] 18 [Stalactites and stalagmites in the Caverns of Sonora, Sutton County, Texas] 19 [Calcite geode from Travis County, Texas] 20 [Petrified wood from Texas Gulf Coastal Plain] 20 [Prospector’s hammer] 22 [Hand lens] 22 [Physiographic outline map of Texas] 42 [Massive anhydrite] 43 [Amphibole asbestos from Gillespie County, Texas] 44 [Barite cleavage fragment from west Texas] 44 [Basalt from Brewster County, Texas] 45 [Calcite has perfect rhombohedral cleavage] 46 [Calcite crystals (dog-tooth spar) from the Terlingua area of Brewster County, Texas] 47 [Celestite cleavage fragment from Lampasas County, Texas] 48 [Cinnabar and calcite crystals from the Terlingua area of Brewster County, Texas] 50 [Bentonite is used as a drilling-fluid additive] 51 [Hazel copper-silver mine, Culberson County, Texas] 53 [Dolomite rock from Burnet County, Texas] 54 [Feldspar cleavage fragment from Llano County, Texas] 55 [Microcline feldspar crystals from Llano County, Texas] 56 [Fluorite has octahedral cleavage] 57 [Galena has perfect cubic cleavage] 57 [Garnet crystal forms] 58 [Gneiss from Blanco County, Texas] 59 [Placer gold in stream gravels] 60 [Granite from Gillespie County, Texas] 61 [Texas State Capitol building at Austin is made of Burnet County granite] 62 [Graphite is used in pencil lead, generator brushes, and lubricants] 63 [Selenite gypsum crystal from Bastrop County, Texas] 64 [Selenite gypsum rosettes from Nolan County, Texas] 64 [Fibrous gypsum from Terlingua area, Brewster County, Texas] 65 [Salt domes occur on the Gulf Coastal Plain] 66 [Specular hematite from Carrizo Mountains, Hudspeth County, Texas] 67 [Limestone from Travis County, Texas] 68 [Limestone quarry at Georgetown, Williamson County, Texas] 69 [Limonite ore is changed to metallic iron in a blast furnace] 71 [Metallic iron is made into steel in an open-hearth furnace] 72 [Magnetite, Llano County, Texas] 73 [Hollandite from Jeff Davis County, Texas] 74 [Precambrian metamorphic marble from Llano County, Texas] 75 [Mica minerals have perfect cleavage in one direction] 76 [Obsidian arrowheads] 77 [Opalized wood from Washington County, Texas] 78 [Quartz-feldspar pegmatite from Burnet County, Texas] 79 [Pyrite veins in white marble from Llano County, Texas] 80 [Cubic crystals of pyrite] 80 [Quartz crystal from Burnet County, Texas] 81 [Amethyst geode from the Alpine area of Brewster County, Texas] 82 [Milky quartz from Burnet County, Texas] 82 [Smoky-quartz crystals from Burnet County, Texas] 83 [Polished agate from Rio Grande gravels of Zapata County, Texas] 83 [Jasper from Uvalde County, Texas] 84 [Sandstone from Zavala County, Texas] 86 [Prospector] 89 [Sulfur is obtained by the Frasch process] 92 [Talc schist from the Allamoore area of Hudspeth County, Texas] 93 [Topaz crystal from Mason County, Texas] 94 [Black tourmaline crystals with milky quartz from Llano County, Texas] 95 [A Geiger counter is used to detect radioactivity] 96