Geyserite
Image: <a href="//commons.wikimedia.org/wiki/User:MiguelHermoso" title="User:MiguelHermoso">Miguel Hermoso Cuesta</a> (CC BY-SA 4.0)
Mineral NameGeyserite
Chemical FormulaSiO2·nH2O
Mohs Hardness5.5
Crystal Systemamorphous
Lusterdull
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity2
Colorswhite, light gray, reddish-brown
Transparencyopaque
Type LocalityGrotto Geyser, Yellowstone National Park, USA
Mineral GroupSilicates (mineraloid)
Usesscientific study, geological interest, collector
Associated Mineralsopal, chalcedony, iron oxides
Raritycommon
Description
The image displays a large, irregularly shaped, light-colored mound of geyserite, forming the cone of the Grotto Geyser, with steam rising from its vents and a pool of reddish-brown water at its base.
Geological Context
Geyserite forms from the rapid precipitation of amorphous silica (SiO2) from supersaturated hot spring waters as they cool and depressurize at the Earth's surface, often building up distinctive sinter terraces and cones around geysers and hot springs in geothermal areas.
