mineral

Likely tumbled black stone or glassy mineral

Indeterminate from image; possibilities include obsidian, hematite, or black tourmaline

AI-generated identification · may be incorrect

Small, dark gray-black, smooth and highly reflective with irregular rounded surfaces; hardness and crystal structure cannot be determined visually. Apparent glassy luster may indicate obsidian, but the image is insufficient for reliable identification.

Identified September 12, 2026More mineral →

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At a glance

Common name: Likely tumbled black stone or glassy mineral
Scientific name: Indeterminate from image; possibilities include obsidian, hematite, or black tourmaline
Category: mineral
Identified: September 12, 2026
Method: Standard

AI Estimated Value

Approximately $1-$10 for a common small tumbled stone; distinctive natural crystals or quality lapidary material may range from $10-$100+.

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

If obsidian, it is volcanic glass formed by rapid cooling of silica-rich lava, generally Quaternary to older Cenozoic. Hematite or tourmaline would form in hydrothermal, igneous, or metamorphic environments.

Uses & applications

Obsidian is used for ornaments and historically sharp tools; hematite is an iron ore and lapidary material; black tourmaline is used in jewelry and mineral collecting.

Geological facts

A streak, hardness test, and examination of fracture surfaces are needed to distinguish these materials. Obsidian commonly shows conchoidal fracture, hematite leaves a red-brown streak, and tourmaline commonly has prismatic striated crystals.

Field identification & locations

Common sources include volcanic regions for obsidian, iron-rich rocks worldwide for hematite, and granitic or metamorphic terrains for tourmaline. Avoid destructive testing if it is a valuable polished specimen.