CRUSH-LEACH ANALYSIS OF FLUID INCLUSIONS IN SMALL NATURAL AND SYNTHETIC SAMPLES

The accuracy and precision of crush-leach analysis of fluid inclusions in quartz, performed using an acidified lanthanum chloride leach solution for analysis of polyvalent cations, has been evaluated. The reproducibility of analysis for thirteen major and trace elements was assessed by comparing results from two splits of each of two samples, separated prior to crushing and cleaning, and was found to be better than 5% in most cases. Crush-leach analysis has also been performed on small samples of ca. 70 mg quartz, and produced results for K, Mg, Fe, Mn, and Zn relative to Na that are indistinguishable from those obtained on portions of several grams of the same samples. This makes possible the selective analysis of inclusions from portions of microthermometry wafers. The miniaturised procedures have been applied to a segment of a synthetic fluid inclusion sample and gave K/Na = 0.579-0.664 (true value 0.656) and Ca/Na = 0.364-0.426 (true value 0.375). This provides proof that crush-leach analysis can accurately yield the fluid inclusion chemistry (provided samples contain one dominant generation of inclusions), although low yields gave bigger uncertainties than for analysis of natural samples.