metamorphic

Polished black-and-white banded stone, likely a dendritic agate or marble

Uncertain; probable calcite marble or chalcedony agate with white mineral veining

AI-generated identification · may be incorrect

Dark gray-black, polished, opaque stone with thin curving white bands or veins and a vitreous to waxy luster. If marble, calcite hardness is about 3 and cleavage is rhombohedral; if agate, chalcedony hardness is 6.5–7 with no cleavage. Specific gravity is approximately 2.6–2.7.

Identified September 17, 2026More metamorphic →

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At a glance

Common name: Polished black-and-white banded stone, likely a dendritic agate or marble
Scientific name: Uncertain; probable calcite marble or chalcedony agate with white mineral veining
Category: metamorphic
Identified: September 17, 2026
Method: Standard

AI Estimated Value

About $3–$20 for a small polished common specimen; potentially $20–$50 if the pattern, finish, and provenance are exceptional.

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

The appearance most strongly suggests a lapidary-polished carbonate or silica-rich specimen; marble forms when limestone recrystallizes during metamorphism, while agate forms by silica deposition in cavities. Geological age cannot be determined from the photograph.

Uses & applications

Likely used as a cabochon, worry stone, or decorative collectible; similar material is also used for ornamental stone and small carvings.

Geological facts

The white lines may be calcite veins, quartz/chalcedony bands, or natural fractures accentuated by polishing. A scratch test and acid test are needed for reliable identification.

Field identification & locations

Commonly encountered as polished material from lapidary markets worldwide. Calcite marble fizzes with dilute hydrochloric acid and is easily scratched by steel; agate does not fizz and resists steel scratching.