mineral
Green Opal
Hydrated amorphous silica (SiO2·nH2O)
AI-generated identification · may be incorrectMohs hardness of 5.5 to 6.5, olive to yellowish-green color, vitreous to greasy luster, amorphous crystal structure with no cleavage.
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Physical properties
Mohs hardness of 5.5 to 6.5, olive to yellowish-green color, vitreous to greasy luster, amorphous crystal structure with no cleavage.
Formation & geological history
Formed at low temperatures from silica-rich water solutions depositing in fissures of near-surface volcanic or sedimentary rocks.
Uses & applications
Used primarily in lapidary work, cabochons, beaded jewelry, and as a collector specimen.
Geological facts
Green opal often gets its coloration from trace amounts of nickel or incorporated plant matter within the silica matrix.
Field identification & locations
Identified by its conchoidal fracture and characteristic waxy luster, commonly sourced from Madagascar, Australia, and Brazil.
