Concentrations of copper occur in sandstone (Whyalla Sandstone Member) and dolomite (Woocalla Dolomite) which rest disconformably on an undulating surface of quartzite (Pandurra Formation) in the Mount Gunson area. Several attempts have been made to mine chalcocite and oxidised copper ores on the floor of Pernatty Lagoon and on the marginal tablelands. Exploration which has been recently undertaken by Noranda Australia Ltd in the same environment south of Pernatty Lagoon has discovered previously unsuspected, widespread, but low grade zinc, lead and copper sulphide mineralisation in dolomitic black shales (Woocalla Dolomite) which underlie the Whyalla Sandstone Member, generally under cover of Quaternary sand. The copper mineralisation appears to be concentrated in sandstone and dolomite adjacent to and within a stromatolite reef complex that formed about a basement high (the Pernatty Culmination), whereas zinc and lead mineralisation, in subeconomic concentrations, occurs in laterally equivalent dolomitic black shales which accumulated in a restricted lagoonal environment, in depressions within the Pandurra Formation.