Mineral

Green Calcite (often commercially called Green Onyx)

Calcium Carbonate (CaCO3)

Hardness: 3 on Mohs scale (can be scratched by a copper coin). Color: Pale to sea-foam green. Luster: Vitreous to waxy. Crystal Structure: Trigonal. Cleavage: Perfect rhombohedral in three directions. Specific Gravity: 2.71.

Hardness: 3 on Mohs scale (can be scratched by a copper coin)
Color: Pale to sea-foam green
Luster: Vitreous to waxy

Identified March 11, 2026More mineral →

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Physical properties

Formation & geological history

Formed through sedimentary processes or hydrothermal deposition. Green calcite specifically gets its color from chlorite or other mineral inclusions trapped during crystallization in carbonate-rich environments. Found in a variety of geological ages from Precambrian to recent.

Uses & applications

Used primarily for decorative carvings, palm stones, architectural accents, and lapidary work. It is also highly popular in the metaphysical and crystal collecting communities.

Geological facts

Despite the trade name 'Green Onyx,' this material is a carbonate (Calcite) rather than a silicate (Onyx/Quartz). It will effervesce (fizz) if a drop of weak hydrochloric acid or white vinegar is applied to a fresh surface.

Field identification & locations

Identify in the field by its characteristic rhombohedral cleavage planes and relative softness compared to quartz. Common locations include Mexico, Brazil, and Pakistan. Collectors should look for translucency and the presence of 'honey' or white banding.

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