Agate
Image: Vassil (Public domain)
Mineral NameAgate
Chemical FormulaSiO2
Mohs Hardness7
Crystal Systemtrigonal
Streak ColorWhite
CleavageNone
FractureConchoidal
Specific Gravity2.6
Colorsreddish-brown, orange, white, grey, dark brown, greenish-grey
TransparencyTranslucent
Type LocalityEsterel, France
Mineral GroupSilicates
Usesjewelry, ornamental objects, collector's items, industrial
Associated Mineralsquartz, calcite, zeolites
Raritycommon
Description
This image displays a polished cross-section of an agate nodule, showcasing intricate concentric and wavy banding in various shades of reddish-brown, orange, white, and grey, with a darker central core and a greenish-grey outer rind.
Geological Context
Agate typically forms in cavities of volcanic rocks, such as basalt or rhyolite, where silica-rich hydrothermal solutions deposit successive layers of cryptocrystalline quartz (chalcedony) over time, creating its characteristic banded structure.
