Horizontally laminated & structurally crinkled gyprock from the Permian of New Mexico, USA.

This is a sample of gyprock (rock gypsum), a finely crystalline-textured, chemical sedimentary rock dominated by the mineral gypsum (CaSO4·2H2O - hydrous calcium sulfate). The whitish-gray layers are the gypsum. The dark brown layers are calcite (CaCO3 - calcium carbonate). Gyprock is an evaporite, which forms by the evaporation of water (usually seawater) and the precipitation of dissolved minerals. Small-scale crinkling is present in the specimen. The original outcrop also had small-scale folding and faulting. These features are the result of early Cenozoic structural deformation, not gypsum-to-anhydrite (or vice-versa) transformations (see Anderson & Kirkland, 1987).

Stratigraphy: Castile Formation, upper Upper Permian

Locality: State Line outcrop, roadcut on either side of Rt. 180/Rt. 62, between Carlsbad Caverns National Park and Guadalupe Mountains National Park, immediately north of the Texas border, southern Eddy County, southeastern New Mexico, USA (32° 00' 34.2" North latitude, 104° 29' 55.0" West longitude)

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