A semi-precious stone consisting of a complex crystalline silicate, which includes aluminum, boron, iron and magnesium, as well as other elements.

Schorl (from German Schörl), or black tourmaline, also sherlite - a mineral of the ring borosilicate subclass; a type of tourmaline, distinguished by the presence of sodium and divalent iron in the crystal lattice. Opaque (unlike other types of tourmaline). It has a rich black color, which is due to the presence of iron atoms. It is used in industry (mainly as a pyroelectric and piezoelectric) and, to a limited extent, in jewelry and for the manufacture of polarizing filters in optics, a rare mineral pigment.

The early history of the mineral schorl shows that the name "schorl" was in use before 1400, because the village known today as Zschorlau (in Saxony, Germany) was then called "Schorl" (or derivatives of this name), and in this village there was a tin mine where, in addition to cassiterite, black tourmaline was found. The first description of schorl under the name "schürl" and its location (various tin mines in the Ore Mountains) was made by Johannes Mathesius (1504–1565) in 1562 under the name "Sarepta oder Bergpostill". Until about 1600, the additional names "Schurel", "Schörle" and "Schurl" were used in German. From the 18th century onwards, the name Schörl was mainly used in German-speaking countries. In English, the names schorl and schirl were used in the 18th century. In the 19th century, the names common schorl, schorl, schorl, and iron tourmaline were the English words used to refer to this mineral.

Magnesium, manganese, and ferric iron may act as impurities instead of divalent iron. As a pigment, it produces beautiful transparent black tones, with hints of green and brown.

•Chemical description: Chemical compound - boron-containing aluminosilicate

•Chemical formula: NaFe2+3Al6Si6O18(BO3)3(OH)4

•Lightfastness - 8

•Alkali resistance:5

•Lime resistance:5

•Acid resistance:5

•ColorIndex no data

•Lens

•Suitability Acrylic, Oil, Tempera, Watercolor / Gouache

•Form powder 25 microns

Color black

Color streak black, greenish-black, brown

Gloss glassy

Transparency Opaque

Hardness 7-- 7.5, but fragile, can be ground even in a bronze mortar.

No cleavage

Uneven fracture

Density 3.18 - 3.22 g/cm³