Everyone expects to find bright, shiny, geometric crystals when they open a geode. However, one of the most common finds when geometric crystals are not present is a geode lined with chalcedony, a microcrystalline variety of quartz.
Microcrystalline chalcedony crystals are so small they cannot be seen with the naked eye. In a geode, a tiny crystal of chalcedony will attach to the wall & it is coated with a layer of tiny chalcedony crystals all pointing outwards from the seed crystal. Layer after layer is deposited, & the early result looks like a small hemisphere attached to the inner surface of the geode. These tiny hemispheres begin to grow into & over one another, and the result is a landscape that looks like a pile of grapes. This hemispherical geometry is a common crystal habit of chalcedony known as botryoidal.
This is a complete Botryoidal Geode from Mexico and a fine specimen for any avid collector. It is not polished & does not fluoresce, however the interior edges of the break do react to UV, indicating agatized chalcedony forming. This is the only one available.
