metamorphic
Marble
Calcite marble; predominantly CaCO₃
AI-generated identification · may be incorrectTypically white to gray with shimmering crystalline surfaces, sugary texture, and irregular veining; Mohs hardness 3–4, vitreous to pearly luster, calcite rhombohedral crystals, and perfect rhombohedral cleavage. The specimen appears foliated or strongly lineated, possibly a marble derived from impure limestone.
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Physical properties
Typically white to gray with shimmering crystalline surfaces, sugary texture, and irregular veining; Mohs hardness 3–4, vitreous to pearly luster, calcite rhombohedral crystals, and perfect rhombohedral cleavage. The specimen appears foliated or strongly lineated, possibly a marble derived from impure limestone.
Formation & geological history
Formed when limestone or dolostone recrystallizes under heat and pressure during regional or contact metamorphism, commonly during mountain-building events. Its exact geological age cannot be determined from the image; the protolith may be far older than the metamorphism.
Uses & applications
Used as dimension stone, sculpture and architectural facing, aggregate, and occasionally as a decorative or lapidary material. Collector value is generally modest unless the texture, color, locality, or fossil content is distinctive.
Geological facts
Calcite marble effervesces vigorously with dilute hydrochloric acid or vinegar, unlike most silicate rocks. Dark streaks may represent graphite, mica, amphibole, or remnants of original bedding.
Field identification & locations
Likely identification requires a hardness test, acid reaction, and inspection of grains; it commonly occurs in metamorphic belts worldwide, including Italy, Greece, Vermont, Colorado, and India. Avoid scratching polished surfaces when testing.
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