metamorphic
Blue-gray calcite-bearing marble
Calcite (CaCO₃), recrystallized as marble; possibly minor quartz or dolomite
AI-generated identification · may be incorrectCoarse, translucent blue-gray to white crystalline mass with glassy-to-pearly luster and prominent cleavage surfaces. Calcite has Mohs hardness 3, rhombohedral cleavage, and specific gravity about 2.71; it should effervesce strongly with dilute hydrochloric acid.
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Physical properties
Coarse, translucent blue-gray to white crystalline mass with glassy-to-pearly luster and prominent cleavage surfaces. Calcite has Mohs hardness 3, rhombohedral cleavage, and specific gravity about 2.71; it should effervesce strongly with dilute hydrochloric acid.
Formation & geological history
Formed when limestone was recrystallized during regional or contact metamorphism, commonly during mountain-building; its exact geological age cannot be determined from the photograph. Blue-gray coloration may reflect trace graphite, clay, or other impurities.
Uses & applications
Calcite marble is used as decorative and facing stone, aggregate, lime feedstock, and occasionally as a lapidary material. Translucent attractive pieces may have modest collector value.
Geological facts
The apparent blocky cleavage and pale translucent crystals favor calcite over quartz, which lacks cleavage. A polished surface would reveal stronger translucency and possible veining.
Field identification & locations
Common in metamorphic belts worldwide, including Italy, Greece, India, Mexico, and the United States. Confirm with a fresh-surface acid test and hardness test; avoid confusing it with nonreactive blue-gray quartzite or dolomite, which reacts weakly when powdered.
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