A METHOD FOR DETERMINING THE NORMATIVE MINERALOGY OF TILLS

A new computer program, NORMA, was developed for calculating the norma tive mineral composition of till from analytical data. The NORMA progr am manipulates concentrations of elements totally dissolved by hot aqu a regia and total element concentrations measured by either total diss olution or X-ray fluorescence method. Minerals dissolving in aqua regi a are presumed to be trioctahedral micas (biotite), clay minerals (chl orite), and primary and secondary salts and hydroxyoxides. The abundan ces of the main silicates (quartz, K feldspar, albite, anorthite and h ornblende) and resistant oxides (ilmenite, magnetite) are determined b y subtracting the concentrations of elements soluble in aqua regia fro m the element concentrations of the total analyses. NORMA gave a relia ble distribution of the main minerals in reconnaissance scale till sam pling in Finland. (C) 1996 Elsevier Science Ltd