A few miles north of Jet, Oklahoma, lies the Great Salt Plains Reservoir. In certain areas of the salt flats can be found unusual selenite (Calcium sulfate or gypsum) crystals that contain included grains of sand. As the selenite crystals form in the muds of the the slat flats, grains of sand become included in the slowly growing crystals. The crystalization process forces the salt grains to conentrate in particular areas in the cyrstals. The result is unusual hourglass figures (See the brownish areas in the above crystals). Selenite crystals are soft and very fragile, but individual specimens and large crystal clusters can be recovered from the sandy muds of the slat plains. (Suite M142,valued at $5.00) Back