This large slice, from a distance, looks like a planetary cross-section.
It is the result of sequential Silica deposition within a Basalt cavity over geological time, each phase recording the chemistry of the groundwater that carried it. The outer border is where the piece's full complexity reveals itself. The Botryoidal Agate has been sliced to expose dozens of individual growth centres in cross-section. Concentric dark rings of varying diameter, each one a discrete episode of mineralisation, clustered and overlapping in dense formation around the entire perimeter.
Mounted on a bespoke stand.
