Calcite

Help improve this record

No owner is registered for this specimen yet. If it's yours or you know more about it, you can add the owner, provenance, publications and other details.

Rich brown masses of manganosite throughout a massive calcite matrix. Quite nice for this rare mineral. The specimen comes with several previous labels, one from the company Burminco, the other from Eric Laskowski. Located in Filipstad Municipality, Varmland, Sweden, the Langban mining district is globally renowned as one of the most mineralogically diverse deposits on Earth. Formed nearly two billion years ago through paleoproterozoic volcanic activity and later regional metamorphism, its stratified iron and manganese ores are hosted within thick dolomitic marble beds. Mining operations began in the sixteenth century to extract iron ore, eventually expanding to manganese until active underground work ended in 1972. The complex metamorphism of these oxygen-poor, manganese-rich skarns produced over three hundred distinct mineral species, including many rare co-type localities. Among these unique minerals is manganosite, a rare manganese oxide that typically appears as dark emerald-green to brownish-black grains or octahedra that alter to dark brown pyrochroite when exposed to air. Today, Langban remains a celebrated location for academic research and specimen collecting.