Siliceous Sinter
Image: <a href="https://en.wikipedia.org/wiki/User:Pseudopanax" class="extiw" title="wikipedia:User:Pseudopanax">Pseudopanax</a> at <a href="https://en.wikipedia.org/wiki/" class="extiw" title="wikipedia:">English Wikipedia</a> (Public domain)
Mineral NameSiliceous Sinter
Chemical FormulaSiO2·nH2O
Mohs Hardness5.5
Crystal Systemamorphous
Lusterdull
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity2.1
Colorswhite, grey, yellow, orange, brown
Transparencytranslucent to opaque
Type LocalityWaimangu Stream, Rotorua, North Island, New Zealand
Mineral GroupSilicates
Usesgeological indicator, scientific study
Associated Mineralsclays, sulfur
Rarityuncommon
Description
The image shows a stream flowing through a trench lined with layered, often porous deposits of siliceous sinter, displaying white, grey, yellow, and orange hues, with some green biological growth.
Geological Context
Siliceous sinter forms from the precipitation of dissolved silica from supersaturated geothermal waters as they cool and degas upon reaching the surface, creating distinctive terraced or mound-like formations in active geothermal areas.
