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
Colorsorange, red, brown, white
Transparencytranslucent
Type LocalityWorldwide, notably Brazil, Uruguay, Mexico, USA
Mineral GroupSilicates
Usesjewelry, ornamental objects, collector
Associated Mineralsquartz, amethyst, calcite, zeolites
Raritycommon
Description
This image displays a polished slice of agate, showcasing concentric bands of vibrant orange, red, and deep brown hues, with a thin white outer rim. The translucent nature of the stone is highlighted by transmitted light, revealing its intricate internal patterns.
Geological Context
Agate forms in the vesicles and cavities of volcanic rocks, where silica-rich hydrothermal solutions deposit layers of chalcedony, often with varying impurities that create its characteristic banding. It can also form in sedimentary rocks.
