Volcanic glass - a rock rather than a mineral, it is a mixture of cryptocrystalline grains of silica minerals in a glass-like suspension, a super-cooled liquid. Obsidian is formed in the latest stage of volcanic eruptions, the silicas left over after most of the other elements and water have been used up are ejected or flow out and rapidly chilled at surface temperatures.
Note on "Transparent/Translucent Obsidian":
A lot of gem-quality water-clear variously coloured 'obsidian' has been offered for sale on the internet (in particular on auction websites) with a variety of sources listed. The material offered for sale is in fact an artificial glass mass-produced in places such as Indonesia.
Visit gemdat.org for gemological information about Obsidian.
Classification of Obsidian
Sub-divisions of Obsidian
Mineralogy of Obsidian
|Glass||An amorphous, homogeneous material with a random liquid-like structure generally formed due to rapid cooling.|
Physical Properties of Obsidian
Synonyms of Obsidian
Other Language Names for Obsidian
Varieties of Obsidian
An iridescent variety of obsidian. Its 'fire' is caused by thin layers of microcrystals of magnetite (which are approximately the thickness of a wavelength of light). The colour of Rainbow Obsidian occurs from a much thicker volume of the specimen (Nadin,...
Obsidian with multicolored iridescence caused by inclusions of magnetite nanoparticles (Nadin, 2007).
A variety of obsidian exhibiting a golden sheen effect.
A rock - a natural volcanic glass containing white 'snowflake' crystal patterns of the mineral cristobalite, originated due to partial crystallisation of the glass.
|Cristobalite||49 photos of Obsidian associated with Cristobalite on mindat.org.|
|Apache Tears||27 photos of Obsidian associated with Apache Tears on mindat.org.|
|Fayalite||14 photos of Obsidian associated with Fayalite on mindat.org.|
|Pyroxene Group||5 photos of Obsidian associated with Pyroxene Group on mindat.org.|
|Quartz||2 photos of Obsidian associated with Quartz on mindat.org.|
|Opal-C||2 photos of Obsidian associated with Opal-C on mindat.org.|
|Spessartine||1 photo of Obsidian associated with Spessartine on mindat.org.|
|Rose Quartz||1 photo of Obsidian associated with Rose Quartz on mindat.org.|
|Jasper||1 photo of Obsidian associated with Jasper on mindat.org.|
|Tiger's Eye||1 photo of Obsidian associated with Tiger's Eye on mindat.org.|
References for Obsidian
Internet Links for Obsidian
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