Tourmaline comes in many colors such as blue, yellow, pink, red, black, green and clear. Green is from iron, chromium and vanadium, pink from manganese. Some crystals are pink at one end and green at the other.
Tourmaline is borosilicate mineral of complex and variable composition. Tourmaline is very abundant and has the best-developed crystals in pegmatites and in metamorphosed limestones in contact with granitic magmas. The colored varieties, when transparent and free from flaws, are cut as gems. Transparent crystals of tourmaline are dichroic - the depth of color varies as the crystal is turned in the light. Another peculiarity of tourmaline is that crystal when heated acquires an electric charge and attracts small objects such as hair or small pieces of paper. Rubbing crystal imparts a similar charge.
Tourmaline came from the Sinhalese name of turmali or tormally (multicolored).
Tourmaline along with opal are birthstones of Libra and it is the anniversary gemstone for the 8th year of marriage.
Three types of tourmaline, distinguished by the predominance of certain elements, are usually recognized: iron tourmaline (schorl), black in color; magnesium tourmaline (dravite), brown; alkali tourmaline, which may be pink (rubellite), green (Brazilian emerald), or colorless (achroite).
As with all gems, protect tourmaline from scratches and sharp blows. Avoid drastic temperature changes. Do not clean tourmaline in a home ultrasonic cleaner.
Tourmaline was known by cenuries by the name schrol. Colored crystals were imported from Sri Lanka at the beginning of the 18th century. During medieval days tourmaline was thought to heal physical and mental disorders as well as prevent death. Used as a gem for over 2,000 years. In addition to its use as a gem, tourmaline is employed in pressure devices because of its piezoelectric properties. It has been used in depth-sounding apparatus and other devices that detect and measure variations in pressure.
The colored crystals of tourmaline are very strongly dichroic-- i.e., they are of different color when viewed in the direction of different axes. Plates cut parallel to the vertical axis of a tourmaline crystal allow only the extraordinary ray through; if two such plates are placed in crossed position, the light is entirely blocked. A pair of these plates form a very simple polarizing apparatus known as tourmaline tongs.
Tourmaline is beautiful in rings, necklaces, and pendants.
Tourmaline is said to dispel fear, negativity and grief. According to legend, the tourmaline of all colors protects the wearer against many dangers and misfortune.
Tourmaline is found in Africa, Brazil, Madagascar, Mexico, Myanmar, Namibia, Sri Lanka, and USA (southern California, Connecticut, Maine, New York and Texas). The Isle of Elba is famous for pink crystals tipped with black which are known as Moors' Heads.