sedimentary

Banded Calcite (Green Onyx)

Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: Green, cream, and tan bands; Luster: Vitreous to waxy; Crystal structure: Trigonal/Hexagonal; Cleavage: Perfect rhombohedral; Specific gravity: 2.71

Hardness: 3 on Mohs scale
Color: Green, cream, and tan bands
Luster: Vitreous to waxy

Identified March 22, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: Green, cream, and tan bands; Luster: Vitreous to waxy; Crystal structure: Trigonal/Hexagonal; Cleavage: Perfect rhombohedral; Specific gravity: 2.71

Formation & geological history

Formed as a chemical sedimentary rock through the precipitation of calcium carbonate from mineral-rich spring water or groundwater, often in caves or around hot springs (travertine/onyx marble).

Uses & applications

Used primarily for decorative items such as spheres, bookends, and ornaments; also popular in metaphysical collections and as interior design accents like tiles and sink basins.

Geological facts

Despite being commercially marketed as 'Green Onyx,' it is geologically calcite or aragonite, not true onyx (which is a form of chalcedony). It is much softer than quartz-based onyx and will react/fizz if exposed to acid.

Field identification & locations

Identify by its characteristic banding, translucency, and low hardness (can be scratched by a steel blade). Commonly found in Mexico, Pakistan, and Afghanistan. Collectors look for vibrant green banding and lack of fractures.