mineralogy-gemmology

Obsidienne, formation, histoire, gisements, utilisation, contrefaçons et usage en lithothérapie

Obsidian, formation, history, deposits, use, co...

Chemical formula : 70–75% SiO2, plus MgO, Fe3O4 (composed mainly of silicon dioxide) Crystal system: amorphous Density: 2.25 to 2.40 Hardness (Mohs scale): 5 to 5.5 Refractive index: 1.480 to 1.500...

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Obsidian, formation, history, deposits, use, co...

Chemical formula : 70–75% SiO2, plus MgO, Fe3O4 (composed mainly of silicon dioxide) Crystal system: amorphous Density: 2.25 to 2.40 Hardness (Mohs scale): 5 to 5.5 Refractive index: 1.480 to 1.500...

2 comments