Zoisite is a calcium aluminium hydroxy sorosilicate belonging to the epidote group of minerals. It was named in 1805 after Austrian scientist and naturalist Baron Sigmund Zois von Edelstein who had a notable mineral collection and identified Zoisite as being a unique mineral species.
Zoisite may be blue to violet, green, brown, pink, yellow, gray, or colorless. Sources of zoisite include Tanzania (tanzanite), Kenya (anyolite), Norway (thulite), Switzerland, Austria, India, Pakistan, and the U.S. state of Washington.
Zoisite is the mineral of some very diverse gem materials including Anyolite or Ruby in Zoisite and Tanzanite, both of which can only be found in Tanzania.
Ruby in Zoisite was discovered at the Longido mining district in northeast Tanzania by Tom Blevins, an English prospector. This is a brilliant green variety of Zoisite associated with medium grade rubies. The red rubies are often distorted and irregularly spread throughout the sea of massive green zoisite. Ruby in Zoisite is also heavily included with black hornblende minerals.
Tanzanite is the most well known variety of the zoisite mineral group. It was discovered in 1967 by Masai tribesman in the hills of Northern Tanzania. It is a transparent blue zoisite that is colored by the presence of vanadium. Some blue zoisite is found naturally but most is produced by heat-treating brown zoisite. The heat changes the oxidation state of vanadium to produce the blue color. Tanzanite is the second most popular blue stone, after sapphire.
Pictured above is my Ruby in Zoisite Sterling Wired Bangle. Below are some more examples of Ruby in Zoisite and Tanzanite jewellery from some members of the Jewelry on Etsy team.