mineral

Green Opal (Prase Opal)

SiO2 · nH2O (Hydrated Silicon Dioxide)

Hardness: 5.5-6 on Mohs scale. Color: Apple-green, yellow-green, to pistacio green. Luster: Waxy to resinous. Crystal structure: Amorphous (non-crystalline mineraloid). Cleavage: None, exhibits conchoidal fracture. Specific Gravity: 1.9-2.3.

Hardness: 5
Color: Apple-green, yellow-green, to pistacio green
Luster: Waxy to resinous

Identified July 22, 2026More mineral →

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Physical properties

Formation & geological history

Formed through low-temperature hydrothermal activity or weathering of ultramafic rocks containing nickel traces, which impart the distinctive green coloration. Commonly found in altered serpentinites and weathered rock zones.

Uses & applications

Used primarily as gemstone material for cabochons, beads, carvings, and as decorative collector specimens. Also appreciated in crystal healing practices.

Geological facts

The green color in this variety of opal is typically caused by inclusions of nickel silicate minerals such as garnierite or chrysotile. Unlike precious opal, green opal usually lacks play-of-color, classified instead as a common opal.

Field identification & locations

Identified by its distinctive yellowish-green hue, waxy to greasy luster, lack of cleavage, and moderate hardness. Commonly found in regions with nickel-rich serpentinite deposits like Madagascar, Tanzania, Australia, and Peru.

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