Home > American Minerals – January 11 > MS2002 Benstonite epitaxy on Calcite

Benstonite epitaxy on Calcite - Sold

Benstonite is a calcium barium magnesium carbonate, originally found as cleavable masses in a baryte deposit in Arkansas. The mineral name honors economic geologist Orlando J. Benston (1901-1966), who first noticed the unusual mineral while working at the type locality. Lippmann (1961) announced the mineral discovery in Naturwissenschaften and followed a year later with a complete description (Lippmann, 1962). The southern Illinois fluorite district, revered for its fine fluorite specimens, also produces “best of species” benstonite; White & Jarosewich (1970) first noted this occurrence.

Benstonite here forms individual disc-shaped crystals, 2-3 mm across, stacked alongside spiky calcite crystals. The benstonite crystals arrange themselves with their crystallographic orientation tied to that of the underlying calcite. This is an epitaxial growth of benstonite on calcite. These stacked benstonite-calcite epitaxial growths resemble pagodas; the largest measures 1.9 cm in this example. This locality is now closed, and this material was never common at the mine.