On the Possibility of Analytical Determination
of Structurally Bound Gold in Sulfide Minerals

V. L. Tauson*, A. Salikhov**, J. Matschullat**, N. V. Smagunov*,
O. I. Bessarabova*, V. I. Men’shikov*, and I. Yu. Parkhomenko*

*Vinogradov Institute of Geochemistry, Siberian Division, Russian Academy of Sciences,
ul. Favorskogo 1a, Irkutsk, 664033 Russia

**Instutute of Environmental Geochemistry, Heidelberg University, 69120 Heidelberg, Germany

Received September 14, 2000

Abstract—The idea of a statistical analysis of the distribution of hydrothermally synthesized single sulfide
crystals using their gold contents is developed specifically to distinguish the structurally bound gold compo-
nent. Mercury was taken as a model example. Similar to gold, mercury shows reduction-aided chemosorption
on sulfides, but its speciation can be directly determined by thermal atomic absorption analysis. It was ascer-
tained that the structurally bound component is best characterized by a set of the lowest values of element con-
centrations with a variation coefficient no higher than 20% (not accounting for the random error of determina-
tion). Proceeding from this result and from previous data on Au distribution, a scheme was elaborated to process
the analytical results for individual crystals in order to characterize the structurally bound Au component. The
main requirement for the analytical method—a combination of a low detection limit and high accuracy—is met
by atomic absorption spectrometry with electrothermal atomization of liquid or solid samples. The optimum
conditions of analysis were determined for sulfide minerals (pyrite, galena, and greenockite). Some modifica-
tions of the method were compared, which demonstrated a reasonable agreement for both low and high Au con-
tents. The application of the method of direct Au determination in solid samples revealed difficulties in the
determination of the structurally bound Au component at high Au concentrations close to the saturation limit,
and it was necessary to analyze fragments of crystalline individuals. A more promising variant of the experi-
mental procedure includes the investigation of phase correspondence in gold-bearing systems with Au-under-
saturated minerals. The perspectives of the direct determination of Au speciation by the method of a stepwise
increase of atomization temperature of solid samples are discussed.


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