The Colors of Tourmaline
inOctober 31, 2012 - 10:58am
Tourmaline is a widely used alternate birthstone for the month of October. Tourmaline is a gem that is available in a fantastic range of colors, so it is an appropriate substitute for Opal, a stone which is known to display a play of colors.
The name comes from the Sinhalese language, from the term Thuramali or Thoramalli or Tura Mali, which literally translates as “mixed stones” or “stones of mixed colors”. The term may have been used to describe the wide range of colored gems available in Sri Lanka, home of the Sinhalese people, long before any of the stones had clear identities of their own. While Brazil and Africa have long surpassed Sri Lanka in production, Sri Lanka would have been an early source of Tourmaline. To this day, terms similar to “Tourmaline” may simply mean a parcel of mixed gem material in some parts of the world, with no serious identification intended.
Europeans were quite used to a non-gem variety of this boron silicate material, a black Tourmaline called Schorl. This material had a practical use. Tourmaline is piezoelectric, meaning that the stone develops an electrical charge when warm. This makes it act like a magnet, attracting small particles at one end, while repelling them at the other. The Dutch used to used the stones to clean their smoking pipes, with the charge attracting small particles of dust and ash. The Tourmaline group is a grpoup of closely related minerals, with 13 other known members. Dravite and Elbaite are other European based members that were identified by the 19th century.
In the world of mineralogy, Tourmalines have several major classifications. Schorl and Buergerite are varieties of Tourmaline that contain iron. Dravite Tourmaline contains magnesium, Liddicoatite contains calcium, and Tsilitite and Uvite varieties of Tourmaline contain manganese. Elbaite, the most widely used Tourmaline, contains lithium. The names these Tourmalines use in the world of jewelry are different. While terms like pink Tourmaline and green Tourmaline are used, Rubellite is used as a name for fine red Tourmaline. Indicolite and Paraiba are used for different types of blue Tourmaline, and fine green Tourmaline may be called Chrome Tourmaline, and this is normally a variety of Dravite that has been colored by chromium or vanadium.
Pink and Green gem varieties are the best known colors in Tourmaline. Some crystals will exhibit both these colors, and will sometimes have a clear layer between these color areas, creating a material referred to as “Watermelon Tourmaline”. Colors can be pale pastels, or bold colors. Intense greens, sometimes called “Chrome Tourmaline”, and vivid red “Rubellite Tourmaline” are beautiful gems. The United States was a major producer of these stones in the 19th century, and some areas of the country still produce fine Tourmalines. Maine and California are the best known sites. The Empress Dowager Tz'u Hsi loved pink and red Tourmalines, and many of the fine red Tourmalines of San Diego County found their way to China. Some historians cite the Empress’ extravagant spending as a contributing factor in the economic problems and rebellion that marked her reign.
While these fine red Rubellite and Chrome Green Tourmalines have been the most esteemed Tourmalines over the years, some of the vivid blue colors have attracted attention in recent decades. While standard blues have been called Indicolite for years, and are rather rare, some neon blue-green material came to market in the late 1980s that was unlike any Tourmaline seen before. Oriignally found in the state of Paraiba in Brazil, soon slightly different material from neighboring states was being sold as ‘Paraiba’. The distinct color cam from trace elements of copper in the chemistry, and copper bearing blue Tourmaline has now also been discovered in Nigeria and Mozambique. While the Mozambique material does resemble some of the material found in the states neighboring Paraiba, controversy still does exist as to the propriety of calling the material Paraiba Tourmaline.
Tourmaline has a history of use in jewelry, and the new varieties that we see coming from Africa promise to keep Tourmaline at the front of gemological developments.