period: Neogene – Miocene (23.03-5.333 million years ago)

excavation site: Machów mine pit, Tarnobrzeg (Subcarpathia)

A dozen or so million years ago, in Miocene there was a warm, shallow sea at the Carpathian foothill. As a result of evaporation of sea water from oversaturated solutions, different chemical sediments precipitated (rock salt and gypsum among others) which settled on hills of the seabed. Due to metasomatic transitions aided by the activity of sulphur bacteria, gypsum transformed into seams of sulphur and celestine. Open-cut Machów mine pit was opened in 1964. The sulphur excavation led to serious contamination and environmental changes which, along with the emergence of abundant cheap sulphur on the market, caused closing of all sulphur pits in Poland.

The piece comes from the collection of Geological Museum of the National Geological Institute – National Research Institute.