Molybdenum $105,389,456 Petroleum 90,494,459 Sand and gravel 32,842,503 Coal 30,251,443 Natural gas 18,695,225 Uranium 18,048,692 Vanadium 15,863,554 Cement 13,377,520 Zinc 13,310,787 Lead 6,582,025 Tungsten 6,360,020 Limestone and dolomite 5,397,570 Silver 4,198,054 Fluorspar 3,887,210 Copper 3,875,976 Stone 1,961,279 Gold 1,832,791 Clay 962,986 Iron 880,047 Pumice 309,370 Tin 278,862 Gypsum 253,856 Pyrites 142,640 All others 1,091,927 Total ($376,288,252) Colorado is now the nation’s leading producer of molybdenum, tin, and vanadium, and second in output of tungsten. In oil production it ranked twelfth among the states in 1968, but ninth in reserves, with 420,000,000 barrels of proven reserves on 1 January 1969. An as yet untapped source of oil lies in the oil shales of western Colorado. As part of the natural environment, water plays a major role in man’s activities. Water problems in Colorado revolve mainly around the best use of runoff in a state whose major catchment basins are across the continental divide from her largest population centers and most fertile farm land. Groundwater, closely related to surface water distribution and movement, is a geological problem, and in Colorado as in other states many government and private geologists serve farm and industrial communities in the search for usable supplies. CAUTION: Old mines are dangerous! They may contain water or deadly gases, or be on the verge of collapse. Keep away from abandoned prospect pits and mine shafts. WARN AND WATCH YOUR CHILDREN. GOLD, SILVER, AND OTHER METALS