Brazilian golden agate slice on brass base

This slice of Brazilian agate is a perfect illustration of the geological phenomena that gave rise to it. It comes from volcanic cavities formed by gas bubbles trapped in basaltic lava, and bears witness to a long process in which successive infiltrations of silica deposited layer after layer of various oxides such as haematite and limonite, responsible for its characteristic hues.
Warm colours dominate this slice: shades of golden brown and orange unfold in concentric layers.
Mounted on a brass base, this slab reveals all its subtlety when the light shines through it (pictures 6,7 and 8), revealing a soft transparency and the details of the different layers formed over time.