Thursday, March 1, 2012

Characteristics Of Tourmaline

Characteristics of Tourmaline


Tourmaline is not a single gemstone but a family of gems that are generally identified by their color. In fact, it's one of the few gemstones in the world that can be found in just about any color. Some tourmaline stones have even been found with two colors in a single stone. Depending on the color, tourmaline can either be very expensive or quite affordable.


Colors


Rubelites are tourmalines that come in dark shades of red, pink and magenta. They are considered some of the most-valuable tourmalines. Pink tourmalines are too pale to be considered rubelites. Orange tourmalines are rare. The most-common version is more of a peach color. Yellow tourmaline is also rare. Green tourmaline is a common stone. The most-common shade will be forest green. It is generally one of the affordable tourmalines, however, if the green is caused by chrome, the stone looks similar to an emerald and more valuable. Paraiba tourmaline are mined in Brazil. They are sparkling shades of teal, aqua and blue and are among the most-valuable gemstones in the world. Indicolite are tourmaline that are typical blue or greenish blue. They tend toward the pale shades. Purple tourmaline is very rare and are mined in Mozambique. Black tourmaline is a common variation and can be found as large stones. It is generally not used as a gemstone. Colorless tourmaline is rare but not expensive since tourmaline is prized for its colors. Bi-color tourmalines contain two and sometimes even three colors in a single stone. Watermelon tourmaline is a bi-color tourmaline that contain green and either pink or red. It is one of the popular tourmaline gemstones.


High-Value Tourmaline


In general, the most-valuable tourmaline gemstones are greater than three carats in size, are clear, perfectly cut and contain one of the rare colors. While cut is the least-important factor, a perfect cut will cause the stone to sparkle more and highlight the color. These rare colors are the red, orange, yellow, forest green, Paraiba (teal, agua, blue), watermelon and bi-color. Paraiba tourmaline can cost $50,000 per carat.


Other Characteristics


Tourmaline is found as long, slender, trigonal crystal. The three-sided crystal is unique to tourmaline as a mineral. When warmed, tourmaline will become charged (positive on one end and negative on the other). The colors of tourmaline are caused by other minerals in the stone (iron creates black tourmaline, magnesium creates yellow, lithium creates any color). Its hardness is equal to quartz.


Occurrence


Tourmaline is found in igneous rocks, particularly granite and pegmatite, and metamorphic rocks, particularly schist and marble. Grains of tourmaline are sometimes found in sandstone. Gemstone-quality tourmaline is generally mined in Brazil and Africa, though deposits of lesser quality have been found in Sri Lanka, Tanzania, Nigeria, Kenya, Madagascar, Mozambique, Namibia, Afghanistan, Pakistan, and the United States. The Paraiba tourmaline was discovered in 1989 and is the source of the very rare tourmalines that are sometimes described as almost neon in their colors.


History


Ancient Egyptians believed that tourmaline passed through a rainbow on its way to earth and picked up its colors from the rainbow. During the Middle Ages, people believed tourmaline could heal both physical and mental problems and even prevent death. Europeans imported colored crystals from Sri Lanka in the 18th Century and was called schrol. The modern name of tourmaline comes from the Sinhalese word turmali, which means multicolored.







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