Abstract

The paragenesis of the secondary Cu minerals is outlined. The free energy for paramelaconite was calculated as -28.12 kcal. indicating its instability at standard conditions. Its relative abundance at this location must be due to an expanded stability of cuprite above log P0 2 = -37.9. Paratacamite, with a free energy slightly less than that of paramelaconite, has a plotted stability field that lies along the atacamite-nantokite boundary making it an intermediate step in the reaction atacamite <--> nantokite.

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