metamorphic

Tumbled gray-and-white stone, likely quartz-rich marble or quartzite

Quartz (SiO₂)–calcite marble or quartzite; exact identification requires testing

AI-generated identification · may be incorrect

Hardness likely Mohs 3–7 depending on composition; gray-white, opaque, with a polished/waxy luster and irregular veining. Quartzite is granular and very hard, while marble is calcite-rich and softer, often reacting with dilute acid.

Identified September 10, 2026More metamorphic →

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At a glance

Common name: Tumbled gray-and-white stone, likely quartz-rich marble or quartzite
Scientific name: Quartz (SiO₂)–calcite marble or quartzite; exact identification requires testing
Category: metamorphic
Identified: September 10, 2026
Method: Standard

AI Estimated Value

Typically $2–$15 for a small tumbled specimen; up to about $20–$50 if strongly patterned or sold as specialty lapidary material.

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

Formed when limestone or quartz-rich sandstone underwent metamorphism under heat and pressure; age varies widely by source locality. The rounded shape is human-tumbled and polished.

Uses & applications

Used as a decorative pebble, lapidary material, aggregate, and occasionally architectural stone; generally low jewelry value unless unusually patterned.

Geological facts

The image alone cannot reliably distinguish marble from quartzite. A steel knife scratches marble but not quartzite; vinegar or dilute hydrochloric acid fizzes on exposed calcite.

Field identification & locations

Commonly found in metamorphic belts worldwide, including the Alps, Appalachians, India, Brazil, and Madagascar. Examine grain texture, test hardness, and check acid reaction on an inconspicuous spot.