mineral

Black tourmaline (schorl) in matrix

Schorl, NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄

AI-generated identification · may be incorrect

Black, vitreous-to-resinous luster; trigonal crystal structure, typically striated lengthwise, with hardness 7–7.5 Mohs and poor cleavage. The photo shows a dark prismatic crystal attached to a rough matrix; composition and identification cannot be confirmed from the image alone.

Identified October 12, 2026More mineral →

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Physical properties

Formation & geological history

Schorl crystallizes from boron-rich granitic pegmatites and hydrothermal veins, often alongside quartz and feldspar. Such deposits formed at varied geological ages, commonly during late stages of granite crystallization.

Uses & applications

Well-formed crystals are collected and sometimes cut as opaque gemstones; tourmaline is also valued in mineral collections and used in limited ornamental applications.

Geological facts

Schorl is the most common tourmaline species and is strongly pleochroic, appearing different shades when viewed from different directions.

Field identification & locations

Look for a black, elongated, often triangular-cross-section crystal with strong lengthwise grooves; common in pegmatites worldwide, including Brazil, Afghanistan, and the United States. A photo cannot establish locality or verify the species.