Skeletal Halites Crystals

Skeletal halite crystals from Sieroszowice mine.
Photo M. Wikiera. Spirifer Minerals specimen.

In late 2016 geologists working in Sieroszowice copper-halite mine, while visit one of the old tunnels, discovered very rich and colorful halite mineralization. The tunnel was located quite far from the active areas of the mine so it was time-consuming and difficult to reach. In the course of several visits geologists were able to collect a few hundred unusual green skeletal halite crystals in spectacular forms.

Skeletal halite crystals from Sieroszowice min Spirifer Minerals specimen.

Geology and Location

The Lubin area (SW Poland) is famous for one of the world’s biggest copper (6th largest producer) and silver (2nd largest producer!) deposits. The deposit is known as Legnica-Głogów Copper District (LGOM) mining kupferschiefer – copper shales. There are over 20,000 miners employed in 3 enormous mines. The average depth of workings is about 1000 m (it varies from 400 m to 1200 m). Several years ago, the total length of tunnels reached over 10,000 km. All mines are operated by a huge national company KGHM Polska Miedź.

Formation of the copper, silver and halite deposits mined in this area is connected with deposition in a late Permian sedimentary basin. At this time part of what is today Europe was covered by relatively shallow epicratonic sea known as Zechstein Sea. Fluctuations of its depth, resulted in several evaporitic events. During those events, deposits of halite and black shale (rich in copper, silver and platinum group elements) were formed in cyclic sequences, known as cyclothemes. The most important ore minerals occur as micro-grains and are visible only under the microscope. Halite, in contrast to the ore minerals, forms layers reaching up to 160 m of thickness! In the Sieroszowice mine both deposits – halite and kupferschiefer – are mined. Halite rich layers are located about 80 m above the copper black shales.