mineral

Tumbled brown-black stone, likely smoky quartz or iron-stained agate

Indeterminate from image; possible quartz (SiO₂), chalcedony, or iron-rich jasper

AI-generated identification · may be incorrect

Dark brown to black, smoothly tumbled, with subdued vitreous-to-waxy luster and lighter brown internal bands or staining. Quartz-group material has Mohs hardness about 7, no obvious cleavage, and conchoidal fracture; exact identification requires testing.

Identified September 3, 2026More mineral →

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At a glance

Common name: Tumbled brown-black stone, likely smoky quartz or iron-stained agate
Scientific name: Indeterminate from image; possible quartz (SiO₂), chalcedony, or iron-rich jasper
Category: mineral
Identified: September 3, 2026
Method: Standard

AI Estimated Value

$1-$5 for a common tumbled stone; approximately $10-$30 if unusually patterned, translucent, or locality-documented.

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

Likely natural silica deposited in volcanic cavities or fractures, later colored by iron oxides and rounded by tumbling. The geological age cannot be determined visually and depends on its source deposit.

Uses & applications

Used mainly as a lapidary, craft, or collectible stone; quartz varieties may be cut into cabochons or beads. It has little value unless it displays attractive banding, translucency, or a recognized locality.

Geological facts

The image may show a small polished mineral specimen rather than a distinct rock type. Stronger identification would require a streak test, hardness test, translucency check, and examination of the unpolished surface.

Field identification & locations

Commonly encountered in mixed tumbled-stone assortments from Brazil, Madagascar, India, or the United States. Quartz should scratch glass but not be scratched by a steel knife; avoid testing valuable material.