Strätlingite

Strätlingite is a rare mineral with the chemical formula Ca3Al2(SiO4)(SO4)2(OH)2. It is a calcium aluminum silicate sulfate hydroxide. It was first discovered in the Långban mine in Filipstad, Värmland, Sweden. The mineral is named after the German mineralogist and chemist Carl Hugo Strätling. Strätlingite typically occurs as small, well-formed crystals. These crystals are often prismatic and transparent to translucent, with a vitreous luster. The color of strätlingite can vary, but it is commonly found as white, colorless, or pale yellow. It is a relatively soft mineral, with a Mohs hardness of around 4 to 4.5. Its density is approximately 2.9 to 3.0 g/cm³.

The formation of strätlingite is associated with metamorphosed manganese and iron ores. It is found in association with other minerals such as calcite, garnet, and vesuvianite. Due to its rarity, strätlingite is not of significant economic importance. However, it is of interest to mineralogists and collectors due to its unique chemical composition and crystal structure.