Agate
Image: Floortje Walraven from The Netherlands (CC BY 2.0)
Mineral NameAgate
Chemical FormulaSiO2
Mohs Hardness6.5
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity2.6
Colorsbrown, orange, white, yellow
Transparencytranslucent
Type LocalityWorldwide (e.g., Brazil, Uruguay, Mexico, USA)
Mineral GroupSilicates (Chalcedony variety)
Usesjewelry, ornamental objects, collector, industrial
Associated Mineralsquartz, zeolites, calcite
Raritycommon
Description
A translucent slice of agate, displaying distinct concentric bands of brown, orange, and white, with a crystalline quartz core, illuminated from behind.
Geological Context
Agate typically forms in cavities of volcanic rocks, such as basalt, where silica-rich solutions deposit successive layers of chalcedony and quartz over time, often filling amygdales or geodes.
