Zoisite
Introduction
Zoisite, named after the Slovenian scientist Sigmund Zois, is a mineral belonging to the group of silicate minerals. It is known for its diverse range of colors and crystal habits. Zoisite is often used in jewelry and is prized for its unique aesthetic qualities.
History
The mineral was first discovered in the Saualpe Mountains of Carinthia in Austria in the 18th century. It was named in honor of Sigmund Zois, who recognized it as a potentially new mineral species. It was later officially described and named by Abraham Gottlob Werner, a German geologist, in 1805.
Physical Properties
Zoisite is a calcium aluminium hydroxy sorosilicate. It has a hardness of 6 to 7 on the Mohs scale, making it a relatively hard mineral. It exhibits perfect cleavage in one direction and good cleavage in another, which can make it challenging to cut for jewelry purposes. The mineral's luster ranges from vitreous to pearly, and its transparency can be transparent to translucent.
Varieties
There are several varieties of Zoisite, each with its unique properties and colors. The most well-known variety is Tanzanite, a blue to violet gemstone that is only found in Tanzania. Another popular variety is Thulite, a pink manganese-bearing variety often used in ornamental carvings. Other varieties include Anyolite, a green zoisite with ruby inclusions, and Saualpite, a colorless to pale yellow variety.
Occurrence and Production
Zoisite occurs in a variety of geological environments. It is often found in metamorphic rocks such as gneiss and schist. It can also occur in igneous rocks like granite. Major deposits of Zoisite are found in Austria, India, Pakistan, Madagascar, and Tanzania.
Uses
Zoisite has several uses, both practical and ornamental. Its hardness and durability make it suitable for use in ceramics and as an abrasive. However, it is most commonly used in the jewelry industry, where its various color varieties are highly prized. Tanzanite, in particular, is one of the most sought-after gemstones in the world.