mineral

Tumbled dark mineral on a polished brown stone slab

Likely quartz-rich chalcedony or jasper slab with a dark metallic mineral inclusion; exact identification is uncertain from the photograph

AI-generated identification · may be incorrect

The brown slab appears translucent to opaque with a smooth, polished surface and waxy luster; the central gray-black piece has a granular or metallic-looking surface. Quartz/chalcedony hardness is about 7 Mohs, while dark inclusions may differ; cleavage is absent in quartz.

Identified August 16, 2026More mineral →

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At a glance

Common name: Tumbled dark mineral on a polished brown stone slab
Scientific name: Likely quartz-rich chalcedony or jasper slab with a dark metallic mineral inclusion; exact identification is uncertain from the photograph
Category: mineral
Identified: August 16, 2026
Method: Standard

AI Estimated Value

Approximately $10-$50 for a common polished specimen; $75-$200+ if the material is confirmed as an attractive, rare, or well-provenanced mineral combination.

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

A polished geological specimen, likely formed from silica-rich groundwater depositing chalcedony or microcrystalline quartz, with a later dark mineral inclusion. Its geological age cannot be determined visually.

Uses & applications

Used mainly for display, lapidary collecting, cabochons, and decorative specimens; quartz-rich material may also be used in abrasives and construction aggregate.

Geological facts

The broad brown piece may be a polished agate or jasper slice, but its lack of visible banding makes a confident agate identification impossible.

Field identification & locations

Test hardness, streak, translucency, and magnetism: quartz-rich material scratches glass and has a white streak; a magnetic dark center could indicate magnetite. Common sources include Brazil, Uruguay, Mexico, India, and the United States.