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(Follow this link for abstracts of past issues)
MORPHOLOGY OF DIAMOND
CRYSTALS FROM THE BINGARA RANGE,
NORTHERN NEW SOUTH WALES, AUSTRALIA
Julian D. Hollis
Cluff Resources Pacific N.L., Hornsby, NSW
ABSTRACT
The crystallography of diamonds from west of Bingara,
NSW reflects progressive chemical corrosion of primary forms. Etching and
resorption features were acquired during complex formational and eruption
events. Many forms are typical of kimberlitic and lamproitic diamonds
world-wide, but there are unusual features not previously described. Some
give evidence of likely eruption histories in an unorthodox mobile-belt
seting, far removed from cratons. Key words: Diamond, crystals, formation,
etching, resorption, Bingara (Australia).
A COMPILATION OF INFRARED ABSORBTION
SPECTRA OF SOME SPECIFIC GEMSTONES
As an aid to their identification
S. Fernandes FGA, M. Khan MDGI, G. Choudhary MDGI
Gem Testing Laboratory, Jaipur, India
ABSTRACT
In the recent past, there has been a growing need
for reliable techniques of gemstone identification. This paper presents a
compilation of infrared absorption spectra for specific gemstones, all of
which appear similar in colour, but otherwise display distinct properties.
Using the transmission mode of the FTIR spectrometer, about 25 samples of
each gem species examined were recorded, keeping in mind the variation that
anisotropic gem minerals have in optical properties with orientation. The
basic objective of this compilation of IR spectra was to provide
'fingerprint' absorption patterns that permit separation of gemstones of
similar colour from each other and, in some cases, natural gemstones from
synthetics. No attempt was made to specify causes for the absorption bands
observed. The major transmission and absorption regions and characteristic
peaks in the IR spectrum of the gemstones investigated for this report are
presented both in spectral and tabular form.
GENESIS AND GEMMOLOGY OF SAPPHIRES FROM THE NEZAMETNOYE DEPOSIT, PRIMORYE REGION, RUSSIA
Alexandr Khanchuk, Boris Zalishchak,
Vera Pakhomova,
Ella Odarichenko, Valeril Sapin FEGI FEBRA RAS,
Vladivostok, Russia
ABSTRACT
This paper describes original Russian research into
inclusions in sapphires from a placer deposit at Nezametnoye in far eastern
Russia, and on heavy fractions of accessory minerals in the gold-bearing
granite-porphyrys that underlie this deposit. Other minerals associated with
these sapphires include zircon and spinel. Chemical analyses of the corundum
and their mineral inclusions are presented. Based on the established
association of this sapphire's mineral inclusions (columbite, albite,
zircon, zinc-bearing hercynite, rutile), the composition of
the sapphire's glassy inclusions, and presence of accessory corundum in the
granite and the granosyenite porphyries that underlie the deposit of
alluvial spahhires at Nezametnoye, the conclusion was made that the sources
of the corundums in this deposit were rare-metal pegmatites, greisens, and
metasomatites associated with Mesozoic granitoid bodies that are widespread
in the area.
