rauhasista

Rauhasiitti is a mineral species belonging to the amphibole group. It is a complex silicate with the chemical formula NaCa2Mg5AlSi8O22(OH)2. Rauhasiitti is known for its distinct blue to purplish-blue color, although variations can occur. It typically crystallizes in prismatic or acicular habit, often found in radiating aggregates.

This mineral is relatively rare and is primarily found in metamorphosed carbonate rocks. It is often associated with other calc-silicate minerals such as diopside, grossular, and scapolite. The formation of rauhasiitti requires specific geological conditions involving high temperatures and pressures, characteristic of regional or contact metamorphism.

Rauhasiitti was first described in 2000 and is named in honor of the Finnish mineralogist Matti Raudasoja. Its type locality is the Långban iron mine in Värmland, Sweden, a location renowned for its diverse and unusual mineral occurrences. While not commercially mined, rauhasiitti is of significant interest to mineral collectors and geologists due to its rarity and unique chemical composition. Microscopic analysis is often required for definitive identification due to its resemblance to other blue amphiboles.