Agate Geode
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 Geode
Chemical FormulaSiO2
Mohs Hardness7
Crystal Systemtrigonal
Lustervitreous
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity2.65
Colorswhite, grey, light brown, pinkish, colorless
Transparencytranslucent
Type LocalityBrazil, Mexico, Uruguay, United States (e.g., Iowa, Illinois)
Mineral GroupSilicates
Usesdecorative items, lapidary, collector specimens
Associated Mineralschalcedony, calcite, zeolites
Raritycommon
Description
This image displays a cross-section of an agate geode, revealing concentric bands of white, grey, and light brown chalcedony surrounding a central cavity lined with sparkling, colorless to pale quartz crystals.
Geological Context
Geodes form in volcanic or sedimentary rocks when mineral-rich water seeps into cavities, depositing layers of silica (chalcedony) on the walls, followed by the growth of quartz crystals towards the center.
