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.

Description: An unusual and rare form of Chalcedony from Cornwall. The mineral forms semi-spherical globular clusters, which have a very pronounced layered structure where exposed. The colour is a pleasing yellow with an interesting waxy surface and texture. A very aesthetic display specimen.

Location: Trevascus Mine, Carnhell Green, Gwinear, Cornwall, England.