mineral
Greenish calcite (likely), possibly talc-bearing marble
Calcite, CaCO₃; green coloration may reflect chlorite, epidote, or serpentine inclusions
AI-generated identification · may be incorrectWhite to pale green, translucent to opaque, vitreous to pearly luster, irregular blocky cleavage, and likely Mohs hardness 3; calcite is trigonal and has specific gravity about 2.71. The specimen appears crystalline and partly foliated or layered, so a marble matrix is also possible.
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Physical properties
White to pale green, translucent to opaque, vitreous to pearly luster, irregular blocky cleavage, and likely Mohs hardness 3; calcite is trigonal and has specific gravity about 2.71. The specimen appears crystalline and partly foliated or layered, so a marble matrix is also possible.
Formation & geological history
Calcite commonly forms from hydrothermal fluids, cavities, or metamorphism of limestone; marble forms during regional or contact metamorphism, generally from Paleozoic to younger protoliths. The green areas likely represent included or intergrown alteration minerals.
Uses & applications
Calcite is used in cement, lime, aggregate, and optical specimens; decorative marble is used for tiles, sculpture, and countertops. Attractive green-and-white pieces are mainly sold as mineral specimens.
Geological facts
Calcite effervesces strongly with dilute hydrochloric acid or vinegar when freshly scratched, unlike quartz. Its three-direction cleavage and relatively soft surface are diagnostic.
Field identification & locations
Common in limestone and marble districts worldwide, including Mexico, the United States, Brazil, and Europe. Test a concealed fresh surface for acid reaction and scratchability; exact identification requires hardness, acid, and possibly microscopy tests.
