mineral

Schorl (Black Tourmaline)

Sodium Iron Aluminum Borosilicate (NaFe3Al6(BO3)3Si6O18(OH)4)

AI-generated identification · may be incorrect

Hardness: 7-7.5 (Mohs); Color: Deep black, opaque; Luster: Vitreous to sub-metallic; Crystal structure: Trigonal/Hexagonal elongated prisms with striations; Cleavage: Indistinct; Specific Gravity: 3.0-3.2

Hardness: 7-7
Color: Deep black, opaque
Luster: Vitreous to sub-metallic

Identified July 19, 2026More mineral →

Explore Schorl (Black Tourmaline) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed in granitic pegmatites, hydrothermal veins, and occasionally in metamorphic rocks like schist or gneiss. These specimens can date from millions to billions of years old depending on the host rock formation.

Uses & applications

Used primarily in metaphysical and jewelry sectors, industrial boron sourcing, and for its pyroelectric and piezoelectric properties in historical scientific instruments.

Geological facts

Black tourmaline is pyroelectric, meaning it becomes electrically charged when heated; it was historically used by Dutch traders to pull ash out of their smoking pipes, earning it the nickname 'Aschentrekker' (ash puller).

Field identification & locations

Identify in the field by its characteristic long, needle-like or chunky prismatic crystals with vertical striations (ridges) along the length. It often has a rounded triangular cross-section and is found in quartz-rich pegmatites worldwide.