Site preferences of Ni/2+/ and Co/2+/ in clinopyroxene and olivine - Limitations of the statistical approach.

Criticism of a statistical approach used by Dasgupta (1972) in analyzing Snyder's (1959) chemical data for minerals from the Duluth Complex in Minnesota. Apart from obvious mathematical objections to citing correlation coefficients to four significant figures from Snyder's relatively inaccurate analytical data, several more fundamental criticisms are leveled at the statistical approach of Dasgupta. These relate to compositional zoning and disequilibrium in the minerals, inhomogeneities of the samples caused by inclusions and exsolved phases, measured site population data for the major cations in olivines and pyroxenes, and the importance of coupled substitutions in the crystal structures. It is concluded that the crystal field predictions of relative enrichments of Ni(2+) and Co(2+) ions in olivine and pyroxene structures have not been disproved by Dasgupta's statistical approach.