Saturday, 9 December 2017

Ethiopian Wello Opals - Imperial Opal

Opal is a hydrated amorphous form of silica; its water content ranges from 3 to 21% by weight, but is usually between 6 and 10%. It is classified as a mineraloid, unlike crystalline forms of silica, which are classed as minerals.

The first report of gem opal from Ethiopia appeared in 1994, with the discovery in the Menz Gishe District, North Shewa Province.
The opal, found mostly in the form of nodules, is of volcanic origin and is found within weathered layers of rhyolite. In 2008, a new opal deposit was found near the town of Wegel Tena, in Ethiopia's Wollo Province.

The Wollo Province opal was different from other Ethiopian opal finds in that it more closely resembled the sedimentary opals of Australia, with a vivid play-of-color. 'Wello' opal became the dominant Ethiopian opal in the gem trade. The finest examples are referred to as 'Imperial Opal'.
These opals are found in a round nodular form within a 3 meter thick layer of welded volcanic ash. Only about 1% of these nodules contain colour.

The colours are very striking with red being common and blue quite rare which is the opposite to Australian opals.
Welo Opals are found in a plateau 2500 to 3299 meters above sea level. Only locals are allowed to mine this field. They work the horizontal level of steep mountains with basic hand tools.
Ethiopia Is considered one of the oldest inhabited human areas on the planet. The Awash Valley has one of the most complete preserved Australopithecine fossils, around 3.2 million years old.