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Abstract Header from the 2009 issue of Gems & Gemology
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.

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Opal from Querétaro, Mexico: fluid inclusion study

The distinctive orange-to-red “fire" opals from Querétaro have not been found in significant quantities at any other locality.

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Green Opal From East Africa

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

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Opals from Opal Butte, Oregon
Opals from Opal Butte, Oregon

Recent mining at Opal Butte in northeastern Oregon has produced a wide variety of large flawless opals.

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Opal from the Shewa Province, Ethiopia

Opal occurs as nodules in volcanic rocks at a new gem opal locality in the Menz Gishe district of Shewa Province, Ethiopia.

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IMG-FA13-Rondeau 154406 300x169
On the Origin of Digit Patterns in Gem Opal

An examination of the finger-like feature mostly found in Ethiopian opal and proposal for its formation.

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Opal from Queretaro, Mexico: Occurrence and Inclusions

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

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Treated Andamooka Matrix Opal
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.

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Queensland Boulder Opal

After almost 75 years of inactivity, the deposits of boulder opal in Queensland, Australia, began to attract new interest in the 1960s and 1970s.

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Chrysoprase and Prase Opal from Haneti, Central Tanzania
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.

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