Volume 23, Number 2, April - June 2007
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(Follow this link for abstracts of past issues)
SPODUMENES FROM NURISTAN, AFGHANISTAN
Lucyna Natkaniec-Nowak
Department of Mineralogy, Petrography and Geochemistry
University of Science and Technology, Krakow, Poland
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ABSTRACT In coloured spodumenes from the Nilaw mine in Nuristan, south-east Afghanistan, substitution of Fe (Fe2+, Fe3+) for A1 in octahedral sites produces green-yellow spodumene, while the admixture of Mn, Fe and possibly Cr ions gives the violet-pink colour to kunzite. These spodumenes are typical products of post-magmatic pegmatitic-pneumatolytic processes. The significant concentration of alkali metals, especially sodium, together with the occurrence of solid inclusions such as muscovite and feldspar in the spodumene crystals indicate that they are petrologically related to Li-bearing granitic pegmatites. |
 Green-yellow spodumene, 136x48x25mm, Nilaw, Nuristan (J.Szczerba Collection). Photo by J. Sinczak |
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SEALANT IMPREGNATED RUBIES G.M. PEARSON Mt Waverley, Victoria
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ABSTRACT In this short paper the author describes some interesting features of several sealant impregnated (glass-filled) rubies that he recently purchased in Melbourne. |
 Specimens of sealant impregnated enhanced rubies that were investigated during this project. |
AGIL REFRACTOMETER & LED LIGHT SOURCE
G.A.A Instrument Evaluation Committee Report
Trevor Linton, Roy Beattie, Brisbane
ABSTRACT
Critical angle refractometers provide essential data for determining
the identity of a gemstone. High quality refractometers are expensive, but
accurate instruments of a moderate price and good quality are now available
on the commercial market. In this report the Committee evaluates one of
these moderately priced instruments, from the AGIL (Asian Gemmological
Institute and Laboratory) in Hong Kong.
USEFULNESS AND LIMITATIONS OF USING ROUTINE FTIR SPECTRA FOR IDENTIFYING GEMSTONES COMPARED WITH THE USE OF CLASSICAL FTIR SPECTRA USING KBR PELLETS
Li Juanjun1, Luo Yueping2, Chen Zhenyu3, Meng Lijuan4
1. National Gold and Diamond Testing Center of China, Jinan, P.R.
China
2. National Jewellery Quality Supervision and Inspection Center of China,
Bejing, P.R. China
3. Institute of Mineral Resources, Chinese Academy of Geological Science,
Bejing 100037, China
4. School of Earth Sciences and Resources, China
ABSTRACT
Infrared spectra can be used to determine the mineralogical species of rough
and facetted gemstones, the presence of enhancement and treatment in
gemstones, and whether a gemstone is natural or synthetic. Although there is
some risk in the routine collection of FTIR spectra, it is easier and
quicker to use than the classical KBr powder method, for infrared spectra
collected using the KBr powder method reveal little information with respect
to value-enhancing treatments, or whether the material under test is natural
or synthetic. By comparing FTIR spectra with IR spectra obtained by the
classical KBr method, the authors were able to establish a routine method
for testing gem materials for macroscopic crystal structure, interaction/s
within polycrystalline aggregates, the configuration and content of O-H in
minerals and rocks. For example, routine FTIR spectra will readily reveal
differences in crystallization between various species of gemstones that
contain a Si02 component.
Key-words: FTIR spectra, routine, gem identification, enhanced and treated, natural and synthetic, crystal structure.
BE AWARE OF AND BEWARE OF OPAL'S DENSITY
Alan Hodgkinson
Portencross, Scotland
ABSTRACT
The author decribes how liquids such as sodium polytungstate and glycerine
can be use practically to discriminate natural opals from synthetic and
all-plastic imitation opals.
NOTES FROM THE GSL LABORATORY
Bill Sechos
GSL, Sydney
ABSTRACT
A selection of three lab reports from Gem Studies Laboratory (GSL) in
Sydney, New South Wales.
FROM A SINGAPOREAN LABORATORY:
MOLDAVITE: NATURAL OR IMITATION?
Tay Thye Sun
Far East Gemological Laboratory, Singapore
ABSTRACT
Two specimens of moldavite were submitted for testing and identification to
the laboratory. Read how the author went about authenticating them.
CIRCLED PIG'S TUSKS
Bobby Mann1, Grahame Brown2, Michael Mahoney3
1. Temple Hills, Maryland, USA
2. Albany Creek, Queensland, Australia
3. Brisbane, Queensland, Australia
ABSTRACT
Two specimens of circled pig's tusks were examined and discovered to be
man-made composite imitations fashioned from an anterior (upper) component
of either cortical bone or X-radiopaque plastic and a posterior (lower)
component of x-radiolucent filled plastic of undetermined composition.
Although superficially resembling natural circled pig's tusks, to the
experienced eye these imitations had structural dissimilarities to the
continuously growing, part enamel covered triangular cross-sectioned tusks
of the male pig or boar..
AGIL PORTABLE LAB SET
G.A.A Instrument Evaluation Committee Report
Trevor Linton, Roy Beattie, Brisbane
ABSTRACT
