NORMA - A PROGRAM TO CALCULATE A NORMATIVE MINERALOGY FOR GLACIAL TILLS AND ROCKS FROM CHEMICAL-ANALYSIS

The NORMA program was developed to calculate a normative mineralogy fo r glacial tills and rocks. The normative mineralogical composition in NORMA is calculated from the proportions of constituents soluble and i nsoluble in hot aqua regia. Constituents insoluble in hot aqua regia w ere determined by subtracting the concentrations of elements soluble i n hot aqua regia from the element concentrations of the total analysis . A test made with the theoretical and actual chemical compositions of minerals showed that the successive distribution of elements into nor mative minerals was most successful when the variability in the chemic al formulae of minerals was small. Since the method includes as normat ive minerals those predominating in acid and intermediate plutonic roc ks and their weathering products, it can be applied only with caution to mafic and ultramafic rocks.