HUGE BLACK shops TOURMALINE Boulder * 7x6x3" - 7.6 Lbs. * Extra Large Crystal Specimen in Quartz Matrix from Brazil

Measurements: 7x6x3" - 7.6 Lbs.
Locality: Minas Gerais, Brazil

This sale is for the huge, Schorl (black tourmaline) crystal specimen in Quartz/Feldspar matrix from Minas Gerais, Brazil pictured.

TOURMALINE PROPERTIES:
Tourmaline is a crystal boron silicate mineral compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. Tourmaline is classified as a semi-precious stone and the gemstone comes in a wide variety of colors. The most common species of tourmaline is schorl. It may account for 95% or more of all tourmaline in nature. The early history of the mineral schorl shows that the name "schorl" was in use prior to 1400 because a village known today as Zschorlau (in Saxony, Germany) was then named "Schorl" (or minor variants of this name). This village had a nearby tin mine where, in addition to cassiterite, black tourmaline was found. The first description of schorl with the name "schürl" and its occurrence (various tin mines in the Saxony Ore Mountains) was written by Johannes Mathesius (1504–1565) in 1562 under the title "Sarepta oder Bergpostill". Up to about 1600, additional names used in the German language were "Schurel", "Schörle", and "Schurl". Beginning in the 18th century, the name Schörl was mainly used in the German-speaking area. In English, the names shorl and shirl were used in the 18th century. In the 19th century the names common schorl, schörl, schorl and iron tourmaline were the English words used for this mineral. The word tourmaline has two etymologies, both from the Sinhalese word turamali, meaning "stone attracting ash" (a reference to its pyroelectric properties) or according to other sources"mixed gemstones".

Color - Most commonly black, but can range from colorless, brown, violet, yellow, orange, blue, red, green, pink, or bi-colored, or even tri-colored.
Crystal habit - Parallel and elongated. Acicular prisms, sometimes radiating. Massive shops. Scattered grains (in granite).
Crystal system - Trigonal.
Cleavage - Indistinct.
Fracture - Uneven, small conchoidal, brittle.
Hardness - 7–7.5.
Luster - Vitreous, sometimes resinous.
Streak - White.
Specific gravity - 3.06 (+.20 -.06).
Density - 2.82–3.32.
Courtesy of Wikipedia