Sineen

Sineen is a rare and unique mineral, primarily composed of calcium silicate hydroxide with the chemical formula Ca6Si6O17(OH)2. It was first discovered in 1975 in the Sineen Mountains of Afghanistan, hence its name. Sineen is known for its distinctive blue color, which is due to the presence of copper impurities. It is typically found in metamorphic rocks, often associated with other minerals such as epidote and calcite.

The mineral has a hardness of 5.5 to 6 on the Mohs scale, making it relatively soft. It has a specific gravity of approximately 3.1 to 3.2, indicating its density. Sineen exhibits a vitreous to pearly luster and can be translucent to transparent. Its crystal system is monoclinic, and it often forms prismatic crystals or granular masses.

Sineen has limited commercial value due to its rarity and the challenges associated with mining in its native region. However, it is of interest to mineral collectors and researchers due to its unique composition and properties. The mineral's discovery has contributed to the understanding of metamorphic processes and the formation of minerals in specific geological environments.