Opals: Opal is a hydrated amorphous form of silica (SiO2·nH2O); its water content may range from 3 to 21% b...
I-Opal, evela eMondulkiri, eCambodia Opal yifomu le-silated amorphous silica (SiO2 · nH2O); okuqukethwe amanzi kungasukela ku-3 kuye ku-21% ...