The largest giant gypsum intergrowths from the Badenian (Middle Miocene) evaporites of the Carpathian Foredeep

Abstract

The Badenian (Middle Miocene) evaporite deposits of the Carpathian Foredeep in Poland, Ukraine and Czech Republic, contain large bottom-grown primary gypsum crystals (selenite) which are some of the largest in the world. The 0.5-3.5 m long crystals are arranged in a palisade manner and create specific intergrowths similar to the contact swallow-tail {101} twins known in other areas. They occur in one stratigraphical interval that is several metres thick. The largest specimens were found near Busko in Southern Poland. The selenite crystals are commonly 1-1.5 m long, but specimens exceeding 2.5 m in length are present but are rare and poorly documented. Some years ago one specimen approaching 3.5 m in length was recognized at Bogucice-Skalki and seems to be the largest known and existing mineral crystal in Poland. Recently another ca. 3.5 m long selenite specimen was exposed at nearby Gacki. Both these crystals are partly damaged, and one is not fully exposed, and therefore it is difficult to establish which is (or was) actually the largest one.