mineraloid
Green Opal
Hydrated amorphous silica (SiO2·nH2O)
Mohs hardness of 5.5 to 6.5, pale to deep green color, vitreous to waxy luster, amorphous crystal structure with no cleavage, specific gravity of 1.9 to 2.3
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Physical properties
Mohs hardness of 5.5 to 6.5, pale to deep green color, vitreous to waxy luster, amorphous crystal structure with no cleavage, specific gravity of 1.9 to 2.3
Formation & geological history
Formed at low temperatures from silica-rich solutions seeping into cracks and cavities in sedimentary or volcanic rocks, often millions of years old
Uses & applications
Used primarily in jewelry, as ornamental stones, and in metaphysical practices
Geological facts
Green opal often gets its coloration from nickel or green silicates trapped within the amorphous silica matrix during formation
Field identification & locations
Identified by its characteristic green hue, conchoidal fracture, and lack of crystal faces; commonly found in countries like Madagascar, Brazil, and Australia
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