BLACK TOURMALINE
Tourmaline is a crystal silicate mineral classified as a semi-precious stone, most commonly black, it can be found in a wide variety of colors, ranging from brown, violet, green and pink, to a dual-coloured pink and green Watermelon Tourmaline. There are quite a few spelling variations of its name, all based around the word Tourmaline. It is also known as Tourmalated Quartz, Tourmalined or Tourmalinated Quartz, as well as Tourmaline in Quartz.
HISTORY
During the early 1900s, Maine and California were the world's largest producers of 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. It is not clear when the first tourmaline was found in California. Native Americans have used pink and green tourmaline as funeral gifts for centuries. The first documented case was in 1890 when Charles Russel Orcutt found pink tourmaline at what later became the Stewart Mine at Pala, San Diego County.
Almost every color of tourmaline can be found in Brazil, especially in the Brazilian states of Minas Gerais and Bahia. The new type of tourmaline, which soon became known as paraiba tourmaline, came in blue and green.
COMPOSITION
The tourmaline mineral group is chemically one of the most complicated groups of silicate minerals. Its composition varies widely because of isomorphous replacement (solid solution), and its general formula can be written as XY3Z6(T6O18)(BO3)3V3W.
HARDNESS
Mohs Scale Hardness: 7 - 7.5
The Mohs scale of mineral hardness is a qualitative ordinal scale characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material.