Zincian chromite from outokumpu, Finland¹

Chromite from the Outokumpu Mine in Finland as described by Vahätälo (1953) has an anomalous composition, ostensibly with RO:R₂O₃ ratio of 0.80 or less. Re-examination by the authors shows that the original analysis apparently overlooked 5.8 per cent ZnO in the chromite; counting this as RO brings the ratio to a more satisfactory 0.96. This zinc content is the highest by far for any chromite reported. Chemical and spectrographic analyses, and x-ray powder data are presented; the cell constant is α = 8.345 Å.

The presence of eskolaite, with abundance of chromium-bearing silicates, and the corrosion of the chromite are believed to be more consistent with hydrothermal alteration of relict chromite stringers in place, than with hydrothermal emplacement of chromite in “dikes” at Outokumpu.