Of 70 recognised marine evaporite deposits in the USA, 61 contain gypsum, 67 anhydrite, 28 halite, 7 bitter salts (sylvite, carnallite or langbeinite) and 1 polyhalite. Most extensive and with the greatest total thickness are those of the mid-continent Permian basin; other thick deposits are the Louann Salt, probably Jurassic, in the Gulf Coast basin, the Pennsylvanian Paradox basin evaporites and the Silurian Salina Group deposits in the Michigan and Appalachian basins, while salts of Cretaceous and Tertiary age are also significant. Most non-marine evaporites are of Quaternary or Tertiary age, earlier deposits being rare and unimportant commercially; since the early Tertiary the Great Basin in the west has hosted a large number of closed-basin drainage systems which have deposited a wide variety of mineral assemblages. They are economic sources of Na and Na-Ca carbonate and bicarbonate minerals, sodium sulphate, halite and borates, while at some the concentrations of aqueous potassium, boron, lithium, bromine, iodine and magnesium allow their recovery from brines. Important Quaternary deposits are Searles Lake and Death Valley in California and Great Salt Lake in Utah, with major Tertiary deposits in the Green River Formation in Colorado and Wyoming. Commercial products of evaporites and brines include salt from 5 major marine basins and Great Salt Lake, potash from the Carlsbad district of New Mexico, Moab in Utah, Great Salt Lake and Searles Lake, gypsum from most marine basins, sulphur from environments such as salt domes, soda ash (Na2CO3) from trona in Green River Basin, Wyoming, and Searles Lake, Na2SO4 and Li from Searles Lake and other brines, borax from California, and Mg, Br and I from sea water and brines in Michigan, Utah, Arkansas and Oklahoma., Of 70 recognised marine evaporite deposits in the USA, 61 contain gypsum, 67 anhydrite, 28 halite, 7 bitter salts (sylvite, carnallite or langbeinite) and 1 polyhalite. Most extensive and with the greatest total thickness are those of the mid-continent Permian basin; other thick deposits are the Louann Salt, probably Jurassic, in the Gulf Coast basin, the Pennsylvanian Paradox basin evaporites and the Silurian Salina Group deposits in the Michigan and Appalachian basins, while salts of Cretaceous and Tertiary age are also significant. Most non-marine evaporites are of Quaternary or Tertiary age, earlier deposits being rare and unimportant commercially; since the early Tertiary the Great Basin in the west has hosted a large number of closed-basin drainage systems which have deposited a wide variety of mineral assemblages. They are economic sources of Na and Na-Ca carbonate and bicarbonate minerals, sodium sulphate, halite and borates, while at some the concentrations of aqueous potassium, boron, lithium, bromine, iodine and magnesium allow their recovery from brines. Important Quaternary deposits are Searles Lake and Death Valley in California and Great Salt Lake in Utah, with major Tertiary deposits in the Green River Formation in Colorado and Wyoming. Commercial products of evaporites and brines include salt from 5 major marine basins and Great Salt Lake, potash from the Carlsbad district of New Mexico, Moab in Utah, Great Salt Lake and Searles Lake, gypsum from most marine basins, sulphur from environments such as salt domes, soda ash (Na2CO3) from trona in Green River Basin, Wyoming, and Searles Lake, Na2SO4 and Li from Searles Lake and other brines, borax from California, and Mg, Br and I from sea water and brines in Michigan, Utah, Arkansas and Oklahoma.