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Abstract
The NORMA program was developed to calculate a normative mineralogy for glacial tills and rocks. The normative mineralogical composition in NORMA is calculated from the proportions of constituents soluble and insoluble in hot aqua regia. Constituents insoluble in hot aqua regia were determined by subtracting the concentrations of elements soluble in 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 normative minerals was most successful when the variability in the chemical formulae of minerals was small. Since the method includes as normative minerals those predominating in acid and intermediate plutonic rocks and their weathering products, it can be applied only with caution to mafic and ultramafic rocks.
Räisänen, M.L., Tarvainen, T. & Aatos, S., 1995: NORMA ‐ a program to calculate a normative mineralogy for glacial tills and rocks from chemical analysis. GFF, Vol. 117 (Pt. 4, December), pp. 215–224. Stockholm. ISSN 1103–5897.