Helvite

Helvite is a rare mineral species of sodium and calcium potassium silicates, with the chemical formula Na5Ca(PO4)2Si6O17. It is a part of the tourmaline group and is also known as helvine.

Helvite is typically found in igneous and metamorphic rocks, often in association with other minerals such as apatite, schorl, and elpidite. It has a glassy to adamantine luster and a pale yellow to yellowish-green color. The mineral has a monoclinic crystal structure and can form tabular or hexagonal crystals.

The name "helvite" comes from the Latin word "Helvetia," which refers to the region of origins in Switzerland. However, the mineral was first discovered in 1847 in Germany, specifically in the Erzgebirge region. Since then, it has been found in other locations around the world, including the United States, Sweden, and Russia.

Helvite is valued by collectors for its rarity and distinctive appearance. However, it is generally considered to be a secondary mineral and is often produced by the alteration of other minerals. As a result, it is not commonly found in significant amounts and is typically seen in small crystals or fragments.