Gypsum in the form of crystals and rosettes of selenite has been found in subsurface clays and sands of the Laguna Madre mudflats of southwest Texas. The habit of the crystals is unusual, and the dominant crystallographic forms are (111) and (102). The manner in which the crystals grow larger at depth and become lens-like in shape also is of interest. It is concluded that the gypsum precipitates from highly saline sea water which periodically moves in windblown sheets across the surface of the mudflats and sinks into the underlying sediments.

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