mineral
Calcite crystal cluster
Calcite (calcium carbonate, CaCO₃), likely on a carbonate matrix
AI-generated identification · may be incorrectCream to translucent-white, vitreous to pearly luster, prominent rhombohedral cleavage, Mohs hardness 3, and specific gravity about 2.71. The bladed/scalenohedral crystal forms and stepped cleavage surfaces are characteristic, though the image does not permit a definitive test.
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Physical properties
Cream to translucent-white, vitreous to pearly luster, prominent rhombohedral cleavage, Mohs hardness 3, and specific gravity about 2.71. The bladed/scalenohedral crystal forms and stepped cleavage surfaces are characteristic, though the image does not permit a definitive test.
Formation & geological history
Likely precipitated from carbonate-rich groundwater or hydrothermal fluids in a cavity or vein; the underlying material may be limestone or another carbonate rock. Calcite is geologically widespread and forms from Precambrian to modern ages.
Uses & applications
Used in cement, lime, aggregate, glass, soil treatment, and chemical manufacture; clear crystals are collectible but generally not jewelry stones because of softness and cleavage.
Geological facts
Calcite effervesces strongly with dilute hydrochloric acid or vinegar, though vinegar may react slowly. It commonly shows double refraction and can fluoresce under ultraviolet light.
Field identification & locations
The specimen is visually consistent with calcite, but aragonite or gypsum are possible alternatives. Around 48.9°N, 2.4°E (Paris region), carbonate rocks and construction-derived material are plausible; test hardness and acid reaction before assigning locality.
