Agate
Image: Hannes Grobe (CC BY-SA 2.5)
Mineral NameAgate
Chemical FormulaSiO2
Mohs Hardness6.5
Crystal Systemtrigonal
Streak ColorWhite
CleavageNone
FractureConchoidal
Specific Gravity2.6
Colorswhite, orange, brown, reddish-brown
TransparencyTranslucent
Type LocalityWorldwide (e.g., Brazil, Uruguay, Mexico)
Mineral GroupSilicates
Usesjewelry, ornamental objects, collector's items
Associated Mineralsquartz
Raritycommon
Description
This image shows a polished slice of agate, revealing concentric bands of white, orange, and reddish-brown chalcedony surrounding a central, irregular cavity.
Geological Context
Agate forms in cavities of volcanic rocks or ancient lavas, where silica-rich solutions deposit successive layers of chalcedony, often creating the characteristic banding.
