mineral
Polished banded calcite pendant (often sold as “onyx marble” or “banded onyx”)
Calcite, CaCO₃; trade name “onyx marble”
AI-generated identification · may be incorrectCream, gray, and honey-brown bands with a polished, waxy-to-glassy luster; trigonal crystal structure and perfect rhombohedral cleavage. Mohs hardness 3; the pendant’s exact stone cannot be confirmed visually.
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Physical properties
Cream, gray, and honey-brown bands with a polished, waxy-to-glassy luster; trigonal crystal structure and perfect rhombohedral cleavage. Mohs hardness 3; the pendant’s exact stone cannot be confirmed visually.
Formation & geological history
Layered calcite precipitated from mineral-rich water, commonly in caves or springs; the bands record changing water chemistry. Such deposits may form in geologically recent settings.
Uses & applications
Carved and polished for pendants, ornaments, and decorative stone; softer than quartz and can scratch or etch with acids.
Geological facts
Despite the name “onyx marble,” this material is calcite, not quartz onyx or true marble formed by metamorphism.
Field identification & locations
Look for curved or parallel bands and test cautiously: calcite is relatively soft and fizzes with dilute acid, unlike quartz. Banded calcite is found in many cave and spring deposits worldwide, including Mexico and Pakistan.
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