metamorphic

Polished banded stone, likely black marble or banded gneiss

Graphitic banded marble or quartz-feldspar biotite gneiss; exact identification requires testing

AI-generated identification · may be incorrect

Dark gray-black, elongated and highly polished, with thin pale linear bands and satin-to-glassy luster. Likely hardness 3–7 depending on composition; massive, non-cleavable appearance, with specific gravity roughly 2.7–2.9.

Identified September 4, 2026More metamorphic →

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At a glance

Common name: Polished banded stone, likely black marble or banded gneiss
Scientific name: Graphitic banded marble or quartz-feldspar biotite gneiss; exact identification requires testing
Category: metamorphic
Identified: September 4, 2026
Method: Standard

AI Estimated Value

Approximately $5–$25 for a common polished specimen; $25–$75 for a larger, especially attractive lapidary piece.

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

Metamorphism recrystallized carbonate or quartz-feldspar-rich rock under elevated heat and pressure, producing compositional banding; age cannot be determined from the image. The shape is human-polished or tumbled.

Uses & applications

Used as a decorative stone, worry stone, paperweight, lapidary piece, or ornamental carving; not typically valuable as jewelry unless unusually attractive or locally significant.

Geological facts

The pale stripes may be calcite, quartz, or feldspar, while the dark matrix could contain graphite, biotite, amphibole, or pyroxene. A streak, hardness, acid, and magnetism test would distinguish marble from gneiss.

Field identification & locations

Commonly sourced from metamorphic terrains worldwide, including India, Brazil, Scandinavia, and North America. Calcite-rich material fizzes with dilute hydrochloric acid and scratches easily; quartz-rich material resists scratching by steel.