Ocos Geodes

Ocos Geodes aka Ochos Occos Geodes

Many names have been given to geodes throughout the world, but none so fitting as the Ocos Geode (some say these are named for their source, the Orinoco River in Brazil, others believe it came from the Portuguese word for "hollow," you decide...) Ocos formed some 130 million years ago in basalt amygdules (a formerly open vesicle which has been filled with secondary minerals precipitated from low temp ground waters which penetrated into the rock).

Over the years the basalts have been weathered away and left behind small geodes in what is now called cascalho, a dark reddish brown soil in the Serra Geral Formation. Ocos are mainly found in the 3000 ft elevations of the Tres Pinheiros (Three Pines) region. The geodes are normally found in the cascalho soil by farmers plowing. Because their skin or outer shell of chalcedony is relatively thin and often rope-like in formation these geodes are easily identified. The Ocos that are found are then taken back down the steep mountains in burlap sacks or buckets on horseback or by pack mules to the town of Soledade to be cut and polished.

Thin shell Ocos called "casa fina" command a higher price, but display less of the famous wavy or flame like patterns on the rim. Ocos size is usually small (1-3 inches) When cut, Ocos display brilliant drusy quartz linings on tan, grey, brown or black shells with white waves or flames. Many Ocos have inclusions in the quartz, rarely amethyst.