42 rock specimens collected from the open cut at Burra were examined in order to comment on a report received from a consulting organisation. Despite a high degree of alteration evident in the samples, it was possible to distinguish microscopically, with varying degrees of confidence, siltstones, shales, dolomites, pyroclastic rocks, lavas and cherts, as components of the original country rocks. 5 successive and often superimposed episodes of rock mineral recrystallization, alteration and mobilisation were distinguished. These in order of succession consist of silicification, replacement by low temperature (non-perthitic) microcline, dolomitisation, kaolinitisation, and diagenetic redistribution of copper carbonates and chalcedonic silica. Primary copper mineralisation, probably emplaced as chalcopyrite, was associated with the formation of microcline, whilst secondary mineralisation, involving the conversion of copper sulphide to malachite, was effected by hydrous solutions present during dolomitisation. Minor redistribution of the rocks' copper content as carbonates and chrysocolla occurred in a final phase of mobilisation.