Black Tourmaline
A species of Tourmaline Group, Also known as Schorl, Cockle, Schorlite Scientific name : Schorl Mineral Group : Tourmaline Group
Black Tourmaline, A species of Tourmaline Group
Also known as:
Schorl, Cockle, Schorlite
Scientific name: Schorl
Mineral Group: Tourmaline Group
Photo By Robert M.Lavinsky , used under CC-BY-SA-3.0 /Cropped and compressed from original 
Description
Not to be confused with other onyx-colored gems, black Tourmaline is packed full of useful elements, making it so much more than a pretty rock. Although it is high in lithium, aluminum, and iron, it is still most commonly used as a semi-precious gemstone and isn't mined for industrial purposes.
Physical Properties
Colors
Bluish-black, brownish-black, greenish-black, black
Luster
VitreousResinous
Diaphaneity
TranslucentToOpaque
Refractive Index
1.635-1.672
Birefringence
0.025
Pleochroism
Very strong: yellow-brown, pale yellow, pale brown
Optical Character
Uniaxial negative
Chemical Properties
Chemical Classification
Silicates
Formula
Na(Fe2+3)Al6(Si6O18)(BO3)3(OH)3(OH)
Elements listed
Al, B, Fe, H, Na, O, Si
Common Impurities
Mn, Mg, Ca, Li, Cr, Ti, F, K
People often ask
General Info
Price
Clarity and weight are the two decisive factors affecting the price of black Tourmaline. At about 2.5 cm across, the price of a higher quality stone is usually $2-$8/piece.
Healing Properties
The most protective of all crystals, black Tourmaline supports the base chakra. It is said to encourage balance and neutrality, release stress, and discharge tension. It also known to dispel anxious feelings and negative emotions, creating a relaxed environment. This stone can apparently be used in homes as a protection grid.
How to Select
Black Tourmaline is a popular gemstone known for its deep, dark color and metaphysical properties. The desirability of black Tourmaline depends on several factors:
1.Color: black Tourmaline should have a rich, opaque, jet-black color. The darker the stone, the more desirable it typically is.
2.Clarity: Although black Tourmaline is generally opaque, stones with fewer visible inclusions or surface blemishes are considered higher quality.
3.Luster: High-quality black Tourmaline has a vitreous luster when polished. Stones that take a good polish and display a uniform shine are especially sought after.
4.Size: Large, well-formed crystals of black Tourmaline are rare and more valuable.
5.Shape and Cut: black Tourmaline is often cut en cabochon or carved into ornamental figures. Quality of the cut and the skill of the lapidary can enhance the desirability of the stone.
6.Treatments: Natural, untreated black Tourmaline is the most desirable. This gemstone is rarely treated or enhanced, but always ensure this with your vendor.
As always, purchase from a reputable dealer to ensure you're getting high-quality stones.
Usage
Black Tourmaline contains small amounts of tin oxide, which can be extracted; thus it is seen as a commercial source of tin. It is also classified as a semi-precious stone, which means that it is in demand for cutting and polishing for use in jewelry and decorations.
Meaning
According to folklore, black Tourmaline is said to enhance artistic creativity and build self-confidence. Native American and African tribes, as well as some Australian aboriginal groups, used the stone to protect themselves against danger.
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, where: X = Ca, Na, K, ▢ = vacancy Y = Li, Mg, Fe, Mn, Zn, Al, Cr, V, Fe, Ti, vacancy Z = Mg, Al, Fe, Cr, V T = Si, Al, B B = B, vacancy V = OH, O W = OH, F, O *Named ferridravite in 1979; renamed to povondraite by the IMA in 1990 Names in existence before the IMA commission existed are in parentheses(). Luinaite-(OH) is a monoclinic distorted variant. A revised nomenclature for the tourmaline group was published in 2011. 
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