metamorphic

Green Onyx (Commercial Marble/Travertine)

CaCO3 (Calcite / Banded Limestone)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: Pale to deep green with reddish-brown and white banding; Luster: Vitreous to waxy when polished; Crystal structure: Trigonal; Specific gravity: 2.71

Hardness: 3 on Mohs scale
Color: Pale to deep green with reddish-brown and white banding
Luster: Vitreous to waxy when polished

Identified August 6, 2026More metamorphic →

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Physical properties

Hardness: 3 on Mohs scale; Color: Pale to deep green with reddish-brown and white banding; Luster: Vitreous to waxy when polished; Crystal structure: Trigonal; Specific gravity: 2.71

Formation & geological history

Formed by the precipitation of calcium carbonate from carbonate-rich waters, typically in hot springs or limestone caves over millions of years.

Uses & applications

Commonly used for ornamental objects, carvings, decorative bowls, tiles, and interior architectural elements.

Geological facts

In the commercial gemstone and stone-carving industry, this material is widely referred to as 'green onyx' or 'Mexican onyx,' though geologists properly classify it as a banded calcite or travertine (a type of limestone).

Field identification & locations

Easily scratched with a knife due to its low hardness (Mohs 3) and will effervesce (fizz) when exposed to dilute hydrochloric acid due to its carbonate composition.