A method for determining the normative mineralogy of tills

A new computer program, NORMA, was developed for calculating the normative mineral composition of till from analytical data. The NORMA program manipulates concentrations of elements totally dissolved by hot aqua regia and total element concentrations measured by either total dissolution or X-ray fluorescence method. Minerals dissolving in aqua regia are presumed to be trioctahedral micas (biotite), clay minerals (chlorite), and primary and secondary salts and hydroxyoxides. The abundances of the main silicates (quartz, K feldspar, albite, anorthite and hornblende) and resistant oxides (ilmenite, magnetite) are determined by subtracting the concentrations of elements soluble in aqua regia from the element concentrations of the total analyses. NORMA gave a reliable distribution of the main minerals in reconnaissance scale till sampling in Finland.