mineral

Black tourmaline (schorl) with host-rock fragments

Schorl, a sodium–iron tourmaline; approximate formula NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄

AI-generated identification · may be incorrect

The black, glassy fragments are consistent with schorl, commonly Mohs 7–7.5, with a trigonal crystal structure and poor cleavage. The gray pieces appear to be associated host rock, but cannot be identified confidently from the image.

Identified September 27, 2026More mineral →

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At a glance

Common name: Black tourmaline (schorl) with host-rock fragments
Scientific name: Schorl, a sodium–iron tourmaline; approximate formula NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄
Category: mineral
Identified: September 27, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a small mixed lot of common rough fragments; well-formed crystals or documented locality specimens may be worth more.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Schorl crystallizes in boron-rich granitic pegmatites and related hydrothermal environments, often alongside quartz and feldspar. Such deposits range from ancient to geologically recent; the specimen’s age and locality cannot be determined visually.

Uses & applications

Tourmaline is used as a gemstone, mineral specimen, and collector material; industrial use is limited. The pictured rough fragments appear mainly suitable for collecting or lapidary sorting.

Geological facts

Schorl is the most common tourmaline species and is typically opaque black. Tourmaline crystals often show strong lengthwise striations and triangular cross-sections.

Field identification & locations

Look for glossy black, elongated, striated crystals; confirm with hardness and crystal form, since other dark minerals can look similar. Tourmaline occurs in pegmatites worldwide, including Brazil, the United States, and Africa.