mineral

Black Tourmaline (Schorl)

Schorl (NaFe3Al6(BO3)3Si6O18(OH)4)

AI-generated identification · may be incorrect

Hardness: 7-7.5 on Mohs scale; Color: Opaque black; Luster: Vitreous to resinous; Crystal Structure: Trigonal; Cleavage: Indistinct; Specific Gravity: 3.0-3.25

Hardness: 7-7
Color: Opaque black
Luster: Vitreous to resinous

Identified July 10, 2026More mineral →

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Physical properties

Hardness: 7-7.5 on Mohs scale; Color: Opaque black; Luster: Vitreous to resinous; Crystal Structure: Trigonal; Cleavage: Indistinct; Specific Gravity: 3.0-3.25

Formation & geological history

Typically forms in felsic igneous rocks, specifically pegmatites, and in metamorphic rocks like schist and marble. It develops through hydrothermal activity involving boron-rich fluids.

Uses & applications

Used extensively in jewelry (as beads or pendants), as a protective stone in metaphysical practices, and historically in scientific instruments due to its piezoelectric properties.

Geological facts

Black tourmaline is both pyroelectric (develops charge when heated) and piezoelectric (develops charge under pressure). It is the most common variety of the tourmaline group, accounting for 95% of all tourmaline in nature.

Field identification & locations

Identified by its jet-black color, lack of transparency, and vertical striations when in raw crystal form. Tumbled specimens are smooth, heavy for their size, and highly reflective. Common in Brazil, Namibia, and the USA.