Awesome deal for brilliantly dyed, cut, and polished agate nodules from Brazil.
Agate is created when circulating ground waters fill a cavity in a host rock (such as volcanic lavas) or dissolve pre-existing material such as bone or shell, thus frequently creating concentric bands like the rings of a tree trunk when split open. Band colors are determined by the differing impurities present in composition of agate. The name agate is derived from the river Achates, in Sicily (now called the Drillo River). It is worth noting that, transparency of agates varies from nearly transparent to opaque. In thin slabs, the opaque agates are mostly translucent.