A geode from the ground that made Brazil the agate capital of the world, cut and polished on one face with the rind left raw.
The deposits in Rio Grande do Sul were found around 1800 by German immigrants from Idar-Oberstein, a town that had been cutting agate for centuries and had just about exhausted its own supply. They recognised what they were standing on, and the stone started going back to Germany to be cut. The trade never really left. Today the Salto do Jacuí district supports around 300 companies and several thousand people, most of them small artisanal operations rather than industrial mines.
The geode itself is older by a distance. It began as a gas bubble in a lava flow, and silica-bearing water worked in later and lined the cavity in layers until it ran out or the space filled.
Blue-grey and white, which is the stone's own colour rather than anything added to it.
Mineral: Agate, banded chalcedony (silicon dioxide, SiO₂)
Crystal system: Trigonal
Origin: Rio Grande do Sul, Brazil
Hardness: 6.5 to 7 on the Mohs scale; durable, though the polished face will dull if knocked about
Treatment: None
Dimensions: 10.34 x 7.4 x 13 cm
Weight: 610 g Note: Cut face polished, exterior left natural
You will receive the exact piece photographed.