Quartz Geode
Image: <bdi><a href="//commons.wikimedia.org/wiki/User:ComputerHotline" title="User:ComputerHotline">Thomas Bresson</a></bdi> (CC BY 3.0)
Mineral NameQuartz Geode
Chemical FormulaSiO2
Mohs Hardness7
Crystal Systemtrigonal
Lustervitreous
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity2.65
Colorsoff-white, light beige, brownish-yellow
Transparencytranslucent
Type LocalityNot specified
Mineral GroupSilicates
Usescollector's item, decorative
Associated Mineralschalcedony, calcite
Raritycommon
Description
This image displays a geode, characterized by an outer layer of light-colored, massive material encasing a hollow interior. The cavity is lined with a druzy coating of numerous small, sparkling, beige to brownish-yellow quartz crystals.
Geological Context
Geodes typically form in sedimentary rocks like limestone or volcanic rocks, where mineral-rich fluids deposit silica or other minerals in pre-existing cavities. The outer shell is often chalcedony (microcrystalline quartz), with larger quartz crystals growing inwards.
