Geode
Image: <a href="//commons.wikimedia.org/wiki/User:Cccefalon" title="User:Cccefalon">CEphoto, Uwe Aranas</a> (CC BY-SA 3.0)
Mineral NameGeode
Chemical FormulaSiO2
Mohs Hardness7
Crystal Systemtrigonal
Lustervitreous
Streak ColorWhite
CleavageNone
FractureConchoidal
Specific Gravity2.65
Colorswhite, clear, brown, orange, blue-grey
TransparencyTransparent
Type LocalityWorldwide
Mineral GroupSilicates
Usescollector, decorative, lapidary
Associated Mineralsquartz, agate, chalcedony
Raritycommon
Description
This image displays a polished cross-section of an agate geode, revealing a hollow interior lined with clear to smoky quartz crystals. The outer rind consists of banded agate in shades of white, blue-grey, orange, and brown, creating a striking contrast with the sparkling crystal cavity.
Geological Context
Geodes form in the cavities of volcanic or sedimentary rocks where mineral-rich water seeps in and deposits layers of silica (chalcedony/agate) and quartz crystals over time, growing inwards towards the center.
