Rhyolite
Image: Aram Dulyan (<a href="//commons.wikimedia.org/w/index.php?title=User:Aramgutang&action=edit&redlink=1" class="new" title="User:Aramgutang (page does not exist)">User:Aramgutang</a>) (Public domain)
Mineral NameRhyolite
Chemical FormulaSilica-rich (felsic) volcanic rock, primarily composed of quartz (SiO2) and feldspar (e.g., KAlSi3O8, NaAlSi3O8, CaAl2Si2O8)
Mohs Hardness6
Streak ColorWhite to light gray
CleavageNone (as a rock)
FractureConchoidal to uneven
Specific Gravity2.3
Colorswhite, gray, pink, tan, light green
TransparencyOpaque
Type LocalityElba, Italy
Mineral GroupIgneous Rock (Felsic Volcanic)
Usesconstruction aggregate, decorative stone, landscaping
Associated Mineralsquartz, feldspar, biotite, hornblende, pyrolusite (as dendrites)
Raritycommon
Description
A light-colored, fine-grained volcanic rock exhibiting dark, fern-like dendritic patterns of pyrolusite on its surface.
Geological Context
Rhyolite is an extrusive igneous rock formed from the rapid cooling of high-silica, viscous magma, typically found in continental volcanic settings.
