Gypsum

specimen number:
9892033

location:
Mt. Gunson, South Australia, Australia

description:
An attractive cluster of gypsum crystals without matrix. In good condition.

Mount Gunson, located on the Stuart Shelf in South Australia, is a prominent historic sediment-hosted copper mining district. Copper was first discovered at the site in 1875, leading to intermittent open-cut mining operations over more than a century until large-scale commercial production largely wound down around 1989, with final activities and dormancy settling in by 2006. Geologically, the deposits are situated on a basement high known as the Pernatty Culmination, where flat-lying Neoproterozoic sedimentary units—such as the Whyalla Sandstone and Woocalla Dolomite—unconformably overlie Mesoproterozoic Pandurra Formation sandstones. The region is famous for producing exceptional mineral specimens, particularly gypsum in the form of transparent selenite crystals. This gypsum forms in the arid, sulfate-rich evaporation environments surrounding adjacent playa lakes like Pernatty Lagoon, often acquiring a distinct light green hue due to the interaction of groundwater with local copper-rich ore bodies.

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