sedimentary
Travertine (commercial 'Onyx')
Calcium Carbonate (CaCO3)
AI-generated identification · may be incorrectHardness of 3 on the Mohs scale, predominantly white to beige with distinct parallel banding, vitreous to dull luster, and trigonal crystal system.
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Physical properties
Hardness of 3 on the Mohs scale, predominantly white to beige with distinct parallel banding, vitreous to dull luster, and trigonal crystal system.
Formation & geological history
Formed through the precipitation of carbonate minerals from supersaturated hot springs or cave waters, commonly developing in limestone-rich environments.
Uses & applications
Widely used for interior decorative tiles, countertops, fireplace surrounds, and carved ornamental objects.
Geological facts
Often marketed commercially as 'Mexican Onyx' or 'Cave Onyx', though it is geologically a travertine limestone rather than true quartz onyx.
Field identification & locations
Identified by its visible layering, relative softness (easily scratched by a knife), and strong effervescence when tested with dilute hydrochloric acid.
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