mineral

Likely black tourmaline (schorl)

Schorl, black tourmaline; NaFe²⁺₃Al₆(BO₃)₃Si₆O₁₈(OH)₄

AI-generated identification · may be incorrect

Appears as a small opaque black, glossy crystal or fragment with possible striations. Tourmaline has Mohs hardness 7–7.5, vitreous luster, trigonal crystal structure, and poor-to-absent cleavage; specific gravity is about 3.0–3.3.

Identified September 13, 2026More mineral →

Explore Likely black tourmaline (schorl) 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

Forms mainly in boron-rich granite pegmatites and hydrothermal veins during late-stage magmatic crystallization, commonly in Precambrian to younger continental crust. The photograph is insufficient to confirm whether it is natural or a polished fragment.

Uses & applications

Used as a collector mineral, ornamental stone, and occasional gemstone; fine crystals may be faceted or sold as protection-themed jewelry. Industrial tourmaline use is limited.

Geological facts

Black tourmaline is strongly pleochroic and commonly develops longitudinal striations. Heating or rubbing can produce pyroelectric or triboelectric charges, attracting tiny particles.

Field identification & locations

Look for a prismatic, three-sided to six-sided form, lengthwise grooves, black color, and hardness greater than glass. Common localities include Brazil, Afghanistan, Pakistan, Madagascar, Namibia, and Maine, USA; confirmation requires tests or a clearer image.