Winter 2011 G&G Lab Notes
This section, from the Winter 2011 issue of Gems & Gemmology, is a compilation of interesting finds from GIA’s laboratories.
Treated Andamooka Matrix Opal
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.
"Opalite": Plastic Imitation Opal with True Play-Of-Colour
A plastic imitation opal that shows true play-of-colour was advertised as "new" and offered for sale under the trade name "Opalite" at the Gem and Lapidary Dealers Association (GLDA) Tucson show in February 1988.
Green Opal From East Africa
Gemmological and chemical analysis of bright green gem-quality opal from Tanzania.
Abstracts; Summer 2009
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.
Leopard Opal: Play-Of-Colour Opal in Vesicular Basalt from Zimapán, Hidalgo State, Mexico
“Leopard opal” consists of vesicular basalt impregnated with play-of-colour opal, and is known only from Zimapán, Hidalgo State, Mexico.
Dyed Purple Hydrophane Opal
Opals with an unusual purple bodycolour and strong play-of-colour have recently appeared in the market.
Play-of-colour opal from Wegel Tena, Wollo Province, Ethiopia
A new opal deposit was discovered in 2008 near the village of Wegel Tena, in the volcanic rocks of Ethiopia’s Wollo Province.
Chrysoprase and Prase Opal from Haneti, Central Tanzania
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.