Chalcedony, Rio Grande do Sul, Brazil
‘Every space is filled, every interstice occupied. Even metal has insinuated itself into the cells and channels from which life has long since disappeared. Compact and insensible matter has replaced the other kind in its last refuge, taking over its exact shapes, running in its finest channels, so that the first image is set down forever in the great album of the ages.’
The Writing of Stones by Roger Caillois (L’ecriture des pierres, 1970).