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Green Opal From East Africa

John I. Koivula and C. W. Fryer, December 1, 1984

Gemmological and chemical analysis of bright green gem-quality opal from Tanzania.

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Opal from Queretaro, Mexico: Occurrence and Inclusions

John I. Koivula, Chuck Fryer, June 1, 1983

An examination of play-of-colour opal from Mexico and its variety of inclusions.

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Chrysoprase and Prase Opal from Haneti, Central Tanzania
Chrysoprase and Prase Opal from Haneti, Central Tanzania

James E. Shigley, Brendan M. Laurs, and Nathan D. Renfro

Commercial quantities of gem-quality chrysoprase and green prase opal (nickel-bearing chalcedony and common opal, respectively) have been recovered from altered serpentinite deposits near Haneti, Tanzania.

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The internal structures of natural pearls from the marine mollusk Pinctada maxima are the subject of the lead article in this issue. The scattered loose pearls on the cover are from Paspaley’s natural pearl collection, which includes one discovered in the 1970s at the Eighty Mile Beach fishing grounds
G&G Spring 2021 Edition
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