Grahame Brown, June 1, 1991
Matrix opal from Andamooka, in South Australia, is a precious opal-included porous rock that is commonly colour enhanced (carbon impregnated) to imitate the highly prized black opal from Lightning Ridge in northern New South Wales, Australia.
Read MoreJohn I. Koivula, Chuck Fryer, June 1, 1983
An examination of play-of-colour opal from Mexico and its variety of inclusions.
Read MoreBrendan M. Laurs, Thomas W. Overton
This article, from the Summer 2009 issue of Gems & Gemmology, is a compilation of abstracts of important gemmology-related articles published outside of Gems & Gemmology.
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