A geode is a hollow rock formation, often spherical or ovoid, that develops inside volcanic or sedimentary rocks. What makes it unique is its interior lined with crystals, such as quartz or amethyst, ...

Slowly, these minerals crystallize, forming a dense lining of quartz or other silicates that can include a variety of crystals like amethyst, calcite or celestite. When a geode splits open ...

They develop when groundwater rich in silica flows through rock and begins building up layers of quartz. If the developing ...

but which makes perfect sense if they are made of quartz. While these crystals are probably similar in shape to the pointy hexagonal prisms found in geodes and gem shops on Earth, each one is only ...

Large crystals found in geodes and other rocks are relatively rare. Pink ChalcedonyA pink chalcedony shows off its beauty. Chalcedonies include many types of cryptocrystalline quartz gems and ...