mineral

Possibly polished black tourmaline (small cut stone)

Tourmaline-group mineral, likely schorl; complex borosilicate, approximately NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄

AI-generated identification · may be incorrect

The image shows a small dark, polished, reflective stone, but the material cannot be identified reliably from appearance alone. If schorl: Mohs hardness 7–7.5, vitreous luster, trigonal crystal system, and poor cleavage.

Identified October 12, 2026More mineral →

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At a glance

Common name: Possibly polished black tourmaline (small cut stone)
Scientific name: Tourmaline-group mineral, likely schorl; complex borosilicate, approximately NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄
Category: mineral
Identified: October 12, 2026
Method: Standard

AI Estimated Value

About $1–$15 if a common small polished stone; identification and quality could change the estimate.

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

Tourmaline crystallizes in granitic pegmatites and some metamorphic rocks as magma cools or fluids alter surrounding rock; specimens may range from ancient to geologically recent.

Uses & applications

Tourmaline is used as a gemstone and mineral specimen; industrial use is limited. This small, dark piece would generally have modest jewelry or collector value.

Geological facts

Dark schorl is the most common tourmaline variety; polished black stones are also commonly sold as onyx, obsidian, or glass, which cannot be distinguished from this photo.

Field identification & locations

The image supports only a tentative identification. Check for natural crystal striations or test hardness; confirm with gemological testing, since glass and other black stones can look similar.