Contamination from mortars and mills during laboratory crushing and pulverizing

Abstract

Contamination of rock samples from laboratory equipment during crushing and pulverizing was investigated. Pulverization using iron and tungsten carbide mortars, and agate and tungsten carbide mills produced three suites of powders. Whole-rock data from the analyses of the three suites of samples enabled assessment of the degree of contamination of samples by coarse crushing and pulverization. The samples analyzed for major and trace elements compositionally represent basalt, basaltic andesite, dacite, and rhyolite. The results from the analyses of major elements exhibit insignificant contamination from the mortars and the mills. The heterogeneity of rock chips explains the compositional differences observed. The tungsten carbide mill contaminated samples with tungsten and cobalt. The significant scatter of other trace elements data is attributed to sample heterogeneity, with no systematic effect from contamination.