PLAY-OF-COLOR OPAL FROM WEGEL TENA, WOLLO PROVINCE, ETHIOPIA

Research areas:

• Surfaces planétaires (2011 - 2016)

Year:

2010

Authors:

• Benjamin Rondeau
• Emmanuel Fritsch
• Francesco Mazzero
• Jean-Pierre Gauthier
• Benedicte Cenki-Tok
• Eyassu Bekele
• Eloise Gaillou

Journal:

GEMS & GEMOLOGY

Volume:

46

Number:

2

Pages:

90-105

Month:

SUM

ISSN:

0016-626X

BibTex:

@article{WOS:000281011000002, author = "Benjamin Rondeau and Emmanuel Fritsch and Francesco Mazzero and Jean-Pierre Gauthier and Benedicte Cenki-Tok and Eyassu Bekele and Eloise Gaillou", abstract = "A new opal deposit was discovered in 2008 near the village of Wegel Tena, in volcanic rocks of Ethiopia{\&}#039;s Wollo Province. Unlike previous Ethiopian opals, the new material is mostly white, with some brown opal, fire opal, and colorless ``crystal{{\&}#039;{\&}#039;} opal. Some of it resembles Australian and Brazilian sedimentary opals, with play-of-color that is often very vivid. However, its properties are consistent with those of opal-CT and most volcanic opals. Inclusions consist of pyrite, barium-manganese oxides, and native carbon Some samples show ``digit patterns{{\&}#039;{\&}#039;}, interpenetrating play-of-color and common opal, resembling fingers. The opaque-to-translucent Wegel Tena opals become transparent when soaked in water, showing a remarkable hydrophane character. White opals from this deposit contain an elevated Ba content, which has not been reported so far in opal-CT. The fire and crystal opals are prone to breakage, while the white, opaque-to-translucent opals are remarkably durable. The proportion of gem-quality material in the Wegel Tena deposit seems unusually high, and 1,500 kg have already been extracted using rudimentary mining techniques. The deposit may extend over several kilometers and could become a major source of gem-quality opal", extra = "PICL", issn = "0016-626X", journal = "GEMS {\&}amp; GEMOLOGY", month = "SUM", number = "2", pages = "90-105", title = "{PLAY}-{OF}-{COLOR} {OPAL} {FROM} {WEGEL} {TENA}, {WOLLO} {PROVINCE}, {ETHIOPIA}", volume = "46", year = "2010", }

Abstract:

A new opal deposit was discovered in 2008 near the village of Wegel
Tena, in volcanic rocks of Ethiopia's Wollo Province. Unlike previous
Ethiopian opals, the new material is mostly white, with some brown opal,
fire opal, and colorless ``crystal{''} opal. Some of it resembles
Australian and Brazilian sedimentary opals, with play-of-color that is
often very vivid. However, its properties are consistent with those of
opal-CT and most volcanic opals. Inclusions consist of pyrite,
barium-manganese oxides, and native carbon Some samples show ``digit
patterns{''}, interpenetrating play-of-color and common opal, resembling
fingers. The opaque-to-translucent Wegel Tena opals become transparent
when soaked in water, showing a remarkable hydrophane character. White
opals from this deposit contain an elevated Ba content, which has not
been reported so far in opal-CT. The fire and crystal opals are prone to
breakage, while the white, opaque-to-translucent opals are remarkably
durable. The proportion of gem-quality material in the Wegel Tena
deposit seems unusually high, and 1,500 kg have already been extracted
using rudimentary mining techniques. The deposit may extend over several
kilometers and could become a major source of gem-quality opal