takistite
Takistite is a rare mineral discovered in 1978. It is a complex borosilicate with the chemical formula Na2Ca2B4Si8O24(OH)2. Takistite crystallizes in the monoclinic system and typically forms prismatic crystals. It is usually colorless or white, but can also be found in shades of yellow, brown, or gray due to impurities. The mineral has a Mohs hardness of 5.5 and a specific gravity of approximately 2.8. Takistite is primarily found in pegmatites and hydrothermal veins, often associated with minerals such as albite, quartz, and tourmaline. It is named after its type locality, the Takist mine in the Czech Republic. Despite its rarity, takistite is of interest to mineral collectors and researchers due to its unique chemical composition and crystal structure.