Sinien

Sinien is a rare and distinctive mineral, known for its vibrant blue color and unique crystal structure. It is a form of calcium silicate, specifically calcium metasilicate, and is classified as a nesosilicate. The mineral was first discovered in 1832 in the Sinian Mountains of China, from which it derives its name. It is typically found in metamorphic rocks, particularly in contact metamorphic zones around granitic intrusions.

Sinien crystals are usually prismatic or tabular, with a hexagonal or pseudo-hexagonal symmetry. They often exhibit a glassy luster and can be transparent to translucent. The mineral's blue color is due to the presence of iron impurities, which can also impart a slight greenish or brownish hue in some specimens. Sinien is relatively soft, with a Mohs hardness of 5 to 5.5, and has a specific gravity ranging from 2.8 to 3.0.

Due to its rarity and aesthetic appeal, sinien is sometimes used as a gemstone. However, its softness and potential for inclusions make it less desirable than some other gemstones. The mineral is also of interest to mineralogists and collectors for its unique crystal structure and distinctive color.