Semi-Precious Gemstones: Schorl
Schorl (Black Tourmaline) used in Jewelry
Source: Brazil, England (Cornwall), Germany (Saxony), Namibia, Pakistan, USA
The semi-precious gemstone known as "schorl" (aks schšrle, schurel, schŸrl, schurl German, afrisite Spanish) is a translucent to opaque mineral variety that belongs to the tourmaline group of minerals. Schorl is typically black or charcoal-gray in color.
Schorl is one of the most common and abundant varieties of tourmaline. The mineral occurs in granitic pegmatites (greisen) found in both igneous, high-temperature hydrothermal veins, and metamorphic rock. Schorl forms long, straight needle-shaped prismatic crystals that terminate in a flat basal face, or trigonal pyramid. Schorl is also piezoelectric and pyroelectric. Schorl is typically associated with greisen, mica, quartz, albite, aquamarine and cassiterite (tin oxide).
The name "Schorl" was derived from Zschorlau, which was the name of a 15th century village in the Saxony Ore Mountains (Erzgebirge) of Germany and Czechoslovakia (now the Czech Republic).
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Schorl Tourmaline (USGS) |
The mineral was first identified in the early 1500s, by a German physician named Ulrich RŸlein von Calw (1465-1523) of Freiberg, who wrote about schŸrl in his book on mining entitled BergbŸchlein [2]. It was also mentioned in the book Sarepta oder Bergpostill, written in 1562 by a German minister named Johannes Mathesius, who lived in the mining town of J‡chymov, in the St. Joachim's valley.
Schorl Crystallography, Chemistry, Physical Properties
Schorl Optical Properties
Bibliography and Reference on Schorl
1. Johann Mathesius, Sarepta oder Bergpostill  . www.uibk.ac.at
1. , Ulrich RŸlein von Calw . www.minrec.org
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