Geode quartz

Quartz GeodeGeode quartz

Quartz geode

Hydrogenous sedimentary rock.
A geode is a crystal filled cavity. They are typically round or oval in shape. This quartz geode came weathered out from a shale bed in the Mississippian age, Borden Formation, Lake Cumberland, Kentucky. The original cavity may have been a gas bubble, root trace, or hole from some other biological origin. 2/2/2021