Fire Opal
Image: <a href="//commons.wikimedia.org/wiki/User:Archaeodontosaurus" title="User:Archaeodontosaurus">Didier Descouens</a> (CC BY-SA 3.0)
Mineral NameFire Opal
Chemical FormulaSiO2·nH2O
Mohs Hardness6
Crystal Systemamorphous
Lustervitreous
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity2
Colorsorange, yellow, red
Transparencytransparent
Type LocalityJalisco, Mexico
Mineral GroupSilicates
Usesjewelry, collector
Associated Mineralsrhyolite, andesite, tridymite, cristobalite
Rarityuncommon
Description
This specimen features vibrant orange and yellow fire opal embedded within a light-colored, fine-grained volcanic matrix, displaying a glassy to resinous luster.
Geological Context
Fire opal forms in volcanic rocks, such as rhyolite and andesite, where silica-rich waters deposit amorphous silica in cavities and fissures at relatively low temperatures.
