Agate
Image: <a rel="nofollow" class="external text" href="https://www.flickr.com/people/14730981@N08">James Petts</a> from London, England (CC BY-SA 2.0)
Mineral NameAgate
Chemical FormulaSiO2
Mohs Hardness7
Crystal Systemtrigonal
Lusterwaxy
Streak Colorwhite
CleavageNone
Fractureconchoidal
Specific Gravity2.65
Colorswhite, orange, brown, grey
Transparencytranslucent
Type LocalityWorldwide, notable localities include Brazil, Uruguay, Mexico, and the USA (Oregon, Montana).
Mineral GroupSilicates
Usesjewelry, ornamental objects, collector specimens, industrial (e.g., mortars and pestles)
Associated Mineralsquartz, calcite, zeolites
Raritycommon
Description
This image displays a backlit slice of agate, revealing intricate concentric banding in shades of translucent white, orange, and brown, with a rough outer rind.
Geological Context
Agate typically forms in the vesicles and cavities of volcanic rocks, where silica-rich hydrothermal solutions deposit successive layers of cryptocrystalline quartz, often creating the characteristic banded patterns.
