metamorphic

Polished gray metamorphic stone, likely marble

Calcite-dominant marble (CaCO₃), possibly dolomitic marble

AI-generated identification · may be incorrect

Gray-white, mottled and veined appearance with a dull-to-satin polished luster; likely granular crystalline texture and no obvious cleavage at this scale. Calcite marble has Mohs hardness 3, specific gravity about 2.7, and effervesces strongly with dilute hydrochloric acid.

Identified September 4, 2026More metamorphic →

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Physical properties

Formation & geological history

Marble forms when limestone or dolostone is recrystallized during regional or contact metamorphism, commonly from Paleozoic or older carbonate rocks. The exact locality and age cannot be determined from the photograph.

Uses & applications

Used for sculpture, architectural facing, tiles, countertops, aggregate, and decorative collecting. A rounded polished specimen has modest value unless it has distinctive veining or provenance.

Geological facts

The gray coloration commonly comes from graphite, pyrite, organic matter, or other impurities; darker streaks may reflect mineral-rich bands or fractures. It may alternatively be a polished limestone or calc-silicate rock.

Field identification & locations

Test an inconspicuous spot with dilute acid: vigorous fizz supports calcite marble or limestone, while weak/no fizz suggests dolomitic marble or another rock. Common sources include Italy, Greece, Turkey, India, and North America; a scratch test and close inspection of grain boundaries would improve identification.