Agate
Image: Hannes Grobe (CC BY-SA 2.5)
Mineral NameAgate
Chemical FormulaSiO2
Mohs Hardness6.5
Lustervitreous
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity2.65
Colorswhite, orange, brown, reddish-brown
Transparencytranslucent
Type LocalityWorldwide (e.g., Brazil, Uruguay, Mexico, USA)
Mineral GroupSilicates
Usesjewelry, ornamental objects, industrial, collector
Associated Mineralsquartz, calcite, zeolites
Raritycommon
Description
A translucent agate geode slice displaying concentric bands of white, orange, and reddish-brown chalcedony, with a central cavity lined by crystalline quartz.
Geological Context
Agate typically forms in cavities within volcanic rocks, such as basalt, where silica-rich solutions deposit successive layers of microcrystalline quartz (chalcedony) over time.
