sedimentary

Green Calcite (Onyx Marble)

Carbonate mineral (Calcium Carbonate, CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 on Mohs scale; Color: Pale green to lime green; Luster: Vitreous to waxy; Crystal Structure: Trigonal/Hexagonal; Cleavage: Perfect rhombohedral; Fracture: Conchoidal.

Hardness: 3 on Mohs scale
Color: Pale green to lime green
Luster: Vitreous to waxy

Identified July 8, 2026More sedimentary →

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Physical properties

Hardness: 3 on Mohs scale; Color: Pale green to lime green; Luster: Vitreous to waxy; Crystal Structure: Trigonal/Hexagonal; Cleavage: Perfect rhombohedral; Fracture: Conchoidal.

Formation & geological history

Formed in sedimentary environments, often through the precipitation of calcium-rich waters in caves (speleothems) or hydrothermal veins. Common in limestone deposits and hot spring areas.

Uses & applications

Used for lapidary work, decorative carving, ornamental sculptures, metaphysical healing practices, and as architectural stone (often mislabeled as 'Onyx' in the tile industry).

Geological facts

Green calcite is often mistakenly referred to as 'German Onyx' or 'Mexican Onyx' in the trade, but it is actually a calcium carbonate rather than a variety of chalcedony. It is highly sensitive to acid.

Field identification & locations

Identified in the field by its low hardness (can be scratched with a copper penny or knife), rhombohedral cleavage, and vigorous effervescence when exposed to dilute hydrochloric acid. Primarily found in Mexico and Brazil.