Opal Limb Casts – Ethiopia
Considered to be one of the finest Opal Limb Casts ever found in Ethiopia.
Tsehey Mewcha, Wegeltena, Wollo Province, Ethiopia.
3.5 cm x 5 cm face X 7 cm long.
Limb casts are formed when Agate is deposited in the vacant cavities of tree branches once covered by hot volcanic ash. The wood itself burned away and left the vacant cavities. The original form of a tree limb is maintained. Some casts may show bark and/or wood textures, or become opalized.
Geologically the region is composed of a horizontal sequence of volcanic basalt and pyroclastic tuff (remains of a collapsed ash cloud) layers. The whole Welo opal deposit is contained in just one of these tuff layers, filling cavities between volcanic debris, bringing us to a conclusion that the whole opalization process occurred between those two volcanic events as no other layer,above or below, shows any signs of opal presence.
At about 10000 ft above sea level local miners must descent a 1000 ft from the top of plateau into the canyon via narrow sharply descending footpaths inaccessible to vehicles or animals, forcing them to carry all necessary equipment themselves each day.
This entry was posted on Tuesday, June 24th, 2014 at 5:16 pm
You can follow any responses to this entry through the RSS 2.0 feed.