mineraloid

Green Opal

Hydrated Silica (SiO2·nH2O)

Hardness: 5.5-6.5 on Mohs scale; Color: Variations of pale green to lime green with potential milky inclusions; Luster: Vitreous to waxy; Crystal Structure: Amorphous; Cleavage: None (conchoidal fracture); Specific Gravity: 1.9-2.3

Hardness: 5
Luster: Vitreous to waxy

Identified April 22, 2026More mineraloid →

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Physical properties

Formation & geological history

Formed from silica-rich water that seeps into cracks and cavities in rocks, particularly in ancient volcanic or sedimentary environments. It is not an igneous, sedimentary, or metamorphic rock, but a mineraloid that precipitates at low temperatures.

Uses & applications

Primarily used in jewelry as cabochons, as tumbled stones for crystal collections, and sometimes in small ornamental carvings or decorative items.

Geological facts

Green opal is often associated with emotional healing and rejuvenation in metaphysical circles. Unlike 'precious opal,' green opal is typically a 'common opal,' meaning it lacks the internal play-of-color (iridescence) but features a beautiful solid or mottled body color.

Field identification & locations

Identify in the field by its waxy luster and smooth, shell-like fracture surfaces. It feels lighter than a typical quartz stone of the same size. Commonly found in Madagascar, Tanzania, Australia, and parts of the United States like Idaho.