Mostly green with purple coming through and some flower formation across the surface.
With this much celadonite showing, it is worth saying where the cavity itself came from. Around 130 million years ago, as South America and Africa began separating, enormous volumes of lava erupted across what is now southern Brazil and set into basalt hundreds of metres thick. Gas trapped in those flows left cavities behind. Every amethyst geode from Rio Grande do Sul sits inside one of them.
Celadonite formed first, lining the empty space as the basalt weathered. Silica-bearing water came later and built quartz on top of it. The green underneath is older than the purple.
Keep it out of direct sunlight. Sustained UV breaks down the iron centres that produce the purple, and amethyst that fades does not come back.
Mineral: Amethyst, the purple variety of quartz (SiO₂), with celadonite
Crystal system: Trigonal
Origin: Rio Grande do Sul, Brazil
Hardness: 7 on the Mohs scale; hard, though fine druzy points chip easily
Treatment: None
Dimensions: 15.5 x 10.2 x 32 cm
Weight: 1.81 kg Note: Supplied on a bespoke gold stand
You will receive the exact piece photographed.