Volcanic Glass
Image: <a href="//commons.wikimedia.org/wiki/User:Strekeisen" title="User:Strekeisen">Strekeisen</a> (CC BY-SA 4.0)
Mineral NameVolcanic Glass
Chemical FormulaAmorphous silicate, predominantly SiO₂
Mohs Hardness5
Crystal Systemamorphous
Lustervitreous
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity2.45
Colorsblack, dark brown, red, green, gray
Transparencytranslucent to opaque
Type LocalityWorldwide in volcanic regions
Mineral GroupAmorphous Silicate (Rock)
Usestools, jewelry, surgical blades, collector's item
Associated Mineralsquartz, feldspar, cristobalite, tridymite
Raritycommon
Description
This microscopic image, taken under plane polarized light, reveals intricate, wavy flow structures characteristic of volcanic glass, appearing in shades of brown, tan, and white.
Geological Context
Volcanic glass forms when felsic lava cools extremely rapidly, preventing the formation of crystalline structures and resulting in an amorphous solid, typically found in extrusive igneous environments.
