The Oxidized Zone of the Broken Hill Lode, N.S.W

A systematic description is given of the remaining outcrops of the Broken Hill lode together with geochemical data. The oxidized lode is characterized by a coronadite-rich gossan in the upper part followed by a complex heterogeneous cerussitic mineralization at depth. The cerussitic zone is in direct contact with the primary sulphide.

Geochemically, the gossans are characterized by an extreme enrichment in manganese and lead. Significant features of the oxide gossan at the surface are a Pb/Fe ratio of about 1 or more and a Pb/Mn ratio of 1 – 2 or greater, even when free of lead carbonate.

The high Pb/Mn ratio in the gossan is caused by the presence of a plumboan variety of corona-dite containing 35%-58% Pb.