gemstone

Green Onyx

Chalcedony (Silicon Dioxide, SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Dark forest green (often dyed); Luster: Vitreous to waxy; Structure: Cryptocrystalline; Cleavage: None; Specific Gravity: 2.6-2.65

Hardness: 6
Color: Dark forest green (often dyed)
Luster: Vitreous to waxy

Identified July 18, 2026More gemstone →

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Physical properties

Hardness: 6.5-7 (Mohs scale); Color: Dark forest green (often dyed); Luster: Vitreous to waxy; Structure: Cryptocrystalline; Cleavage: None; Specific Gravity: 2.6-2.65

Formation & geological history

Formed by the deposition of silica in gas cavities (vesicles) in volcanic lavas, or in veins within sedimentary rocks. While natural green chalcedony exists (Chrysoprase), most dark 'Green Onyx' is historically microcrystalline quartz that has been dyed for color uniformity.

Uses & applications

Primary use is in jewelry, such as rings, pendants, and beads, as well as ornamental carvings and decorative cabochons.

Geological facts

While the term 'Onyx' usually refers to black and white banded stones, in the jewelry trade, 'Green Onyx' is a widely accepted marketing name for dyed green chalcedony. It was highly valued in ancient Egypt and Greece for protective amulets.

Field identification & locations

Identify by its smooth, waxy texture and uniform deep green color. Field identification is difficult due to its microcrystalline nature, requiring laboratory testing to differentiate from jade or dyed glass. Often found in Brazil, India, and Madagascar.