Are tourmalines rare?
Most colors are fairly common, but pure blue, red, orange, yellow, and purple stones are rare. Such stones usually command higher prices. Color-change tourmalines are also exceptionally rare.
Where are tourmalines found?
Gem and specimen tourmaline is mined chiefly in Brazil and many parts of Africa, including Tanzania, Nigeria, Kenya, Madagascar, Mozambique, Malawi, and Namibia.
How are tourmalines formed?
Tourmaline is produced in pegmatites. These are voids deep under ground that are filled with a rich hot liquid that is rich in different minerals. When the liquids begin to cool, the minerals crystallize and form Tourmaline crystals. The host rock around these pegmatites is generally granite or schits.
What does June birthstone look like?
Or select alexandrite as your June birthstone Alexandrite possesses an enchanting chameleon-like personality. In daylight, it appears as a beautiful green, sometimes with a bluish cast or a brownish tint. However, under artificial lighting, the stone turns reddish-violet or violet.
Where do tourmalines come from?
During the early 1900s, Maine and California were the world’s largest producers of gem tourmalines. The Empress Dowager Cixi of China loved pink tourmaline and bought large quantities for gemstones and carvings from the then new Himalaya Mine, located in San Diego County, California.
How to identify paraiba tourmaline?
Any blue tourmaline that is diamagnetic can be identified as paraiba tourmaline colored by copper in contrast to magnetic blue tourmaline colored by iron. Some tourmaline gems, especially pink to red colored stones, are altered by heat treatment to improve their color. Overly dark red stones can be lightened by careful heat treatment.
What is the nomenclature for the tourmaline group?
A revised nomenclature for the tourmaline group was published in 2011. Tourmaline is a six-member ring cyclosilicate having a trigonal crystal system. It occurs as long, slender to thick prismatic and columnar crystals that are usually triangular in cross-section, often with curved striated faces.
What are the characteristics of tourmaline?
Tourmaline is distinguished by its three-sided prisms; no other common mineral has three sides. Prisms faces often have heavy vertical striations that produce a rounded triangular effect. Tourmaline is rarely perfectly euhedral. An exception was the fine dravite tourmalines of Yinnietharra, in western Australia.