metamorphic
Tumbled zebra calcite (likely calcite marble)
Calcite, CaCO₃; commonly recrystallized limestone/marble with dark graphite- or carbon-rich bands
AI-generated identification · may be incorrectPolished, rounded specimen with white to gray calcite and black-brown banding; vitreous to pearly luster, Mohs hardness 3, rhombohedral cleavage, and specific gravity about 2.7. Effervesces readily with dilute hydrochloric acid or vinegar, though the polish may inhibit reaction.
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Physical properties
Polished, rounded specimen with white to gray calcite and black-brown banding; vitreous to pearly luster, Mohs hardness 3, rhombohedral cleavage, and specific gravity about 2.7. Effervesces readily with dilute hydrochloric acid or vinegar, though the polish may inhibit reaction.
Formation & geological history
Forms when limestone is metamorphosed and recrystallized, with carbonaceous impurities producing the dark bands; the geological age varies by deposit. The specimen has been cut and tumbled, obscuring its original fabric.
Uses & applications
Used as a decorative stone, lapidary material, cabochons, carvings, and ornamental objects; softer than quartz and generally unsuitable for high-wear jewelry or major construction applications.
Geological facts
The strong black-and-white pattern is commonly marketed as “zebra calcite” or “zebra marble,” names that can refer to several visually similar carbonate rocks.
Field identification & locations
Likely sources include Mexico, Pakistan, and other carbonate-hosting regions. Distinguish it from zebra jasper by its softness and acid reaction; a steel nail can scratch calcite.
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