Agate
Image: Hannes Grobe (CC BY-SA 2.5)
Mineral NameAgate
Chemical FormulaSiO2
Mohs Hardness7
Crystal Systemtrigonal
Lustervitreous
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity2.65
Colorsred, white, orange, brown
Transparencytranslucent
Mineral GroupSilicates
Usesjewelry, ornamental objects, collector
Associated Mineralsquartz, calcite, zeolites
Raritycommon
Description
This image displays a polished slice of agate, revealing concentric bands of deep red, white, and orange, with a rougher outer rind. The bands form intricate patterns, characteristic of agate's layered growth.
Geological Context
Agate forms in the vesicles and cavities of volcanic rocks or other host rocks, where silica-rich fluids deposit layers of chalcedony over time. These layers often conform to the shape of the cavity, creating the distinctive banded patterns.
