The occurrence of trace elements in coal

The standard comparison of relationships of trace element concentrations in coal is based on a comparison of mean values of elemental concentrations. This method is extended by including some functions of covariances among trace element concentrations. In the proposed method, the comparison is based on: the pattern of the mass spectrum of mean values of concentrations; the spectrum of the covariance matrix; the eigenvectors of the covariance matrix; and the order of eigenvectors. The method has been applied to the coal of the Istrian coal basin and the same genesis of the elements calcium, sulphur, iron, titanium and vanadium throughout the considered coal seam has been established.