vesuvianitt

Vesuvianite, also known as idocrase, is a complex silicate mineral with the chemical formula approximately Ca19(Al,Mg,Fe)13(Si2O7)4(SiO4)2(OH)10. It is found in metamorphic rocks, particularly in contact-metamorphosed limestones and dolomites, as well as in some mafic volcanic rocks. Its color can vary widely, ranging from yellow, green, brown, to bluish or purplish, and it can be transparent to translucent. The name vesuvianite comes from its type locality, Mount Vesuvius in Italy, where it was first discovered.

The mineral typically crystallizes in prismatic or pyramidal forms, often with striated faces. It is known for its vitreous to resinous luster and has a hardness of 6 to 7 on the Mohs scale, making it moderately hard. While often found in massive form, well-formed crystals are prized by collectors. Idocrase, the alternative name, was given by Abraham Gottlob Werner in 1795, referring to its common appearance as a mixture of other minerals.

Vesuvianite is not a particularly common gemstone, but some varieties, especially those with a rich color and clarity, are cut and polished for ornamental purposes. Certain gem-quality specimens, particularly those from regions like Quebec, Canada, are known as californite when they exhibit a jade-like appearance due to their color and texture. It is generally considered a collector's mineral rather than a significant economic resource, though it can be an indicator of specific metamorphic conditions.