mineral

Polished black stone, likely black jasper or basalt

Most likely microcrystalline quartz (black jasper/chert), SiO₂; basalt is a plausible alternative

AI-generated identification · may be incorrect

Smooth tumbled surface, dark gray-black color, subdued vitreous-to-waxy luster, and no visible crystals or cleavage. Likely hardness about 6.5–7 if jasper/chert, or 5–6 if basalt; specific gravity roughly 2.7–3.0.

Identified August 13, 2026More mineral →

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At a glance

Common name: Polished black stone, likely black jasper or basalt
Scientific name: Most likely microcrystalline quartz (black jasper/chert), SiO₂; basalt is a plausible alternative
Category: mineral
Identified: August 13, 2026
Method: Standard

AI Estimated Value

Typically $2–$15 for a single tumbled piece; approximately $10–$40 if unusually large, exceptionally polished, or confirmed as attractive black jasper.

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

Black jasper forms when silica-rich fluids replace or cement volcanic/sedimentary material; basalt forms from rapidly cooled mafic lava. The specimen’s geological age and exact origin cannot be determined from the photograph.

Uses & applications

Commonly sold as a low-cost tumbled stone for décor, meditation, cabochons, and jewelry; basalt is also widely used as aggregate and building stone.

Geological facts

The even black color and polished finish are consistent with jasper, chert, basalt, or artificially treated stone. A strong glassy streak or tiny crystals would favor basalt, while a white streak and conchoidal fracture would favor jasper/chert.

Field identification & locations

Test inconspicuously: jasper/chert can scratch ordinary glass and leaves a white streak; basalt usually cannot scratch glass and may show fine specks. Common sources include India, Brazil, Mexico, and the western United States.