Mineral Species: Quartz var. Chalcedony

Chemical Formula: SiO2

Chemical Name: Silicon Dioxide

Mineral Class: Tectosilicate

Mineral Notes: Chalcedony is a microcrystalline variety of quartz, frequently occurring as botryoidal masses. It forms by the slow precipitation of silica from aqueous solution and is found in a huge variety of shapes and forms. Recently Chalcedony has been shown to be a mixture of Quartz and Moganite, another silica mineral.

Description: A post-volcanic vesicle geode which has been split in half to expose the Chalcedony interior. The mineral forms numerous botryoidal formations and finger-like protrusions. The mineral is extremely lustrous and many small crystals can also be seen. It displays exceptionally well under a good light source.

Location: Kozákov, Liberec, Bohemia, Czech Republic.