The procedures generally used in prospecting for sulfide ore bodies are discussed. It is shown that entirely different circumstances govern the search for massive sulfide ore bodies compared with those involved in prospecting for disseminated sulfide deposits.

Massive sulfide deposits are excellent electrical conductors which commonly yield strong anomalies during rapid reconnaissance electromagnetic survey procedures. The difficulty in detecting them is that there are hundreds of barren non-sulfide geological conductors for every sulfide mass. For this reason the biggest problem in prospecting for massive sulfide ore bodies generally is that of devising means of screening large numbers of equally promising targets to find those few which are most likely to be rich in sulfides. Facts are presented to show that the screening processes can be carried out rapidly, thoroughly, and economically by intensive use of the gravity meter and the portable refraction seismograph.

The induced polarization method is the only geophysical procedure which responds to buried, disseminated, metallic mineral deposits. It is, therefore, widely used in prospecting for buried porphyry copper ore bodies. The feasibility of and need for extensive calculations of the induced polarization responses of geological bodies of simple geometrical form is explained. Examples are presented which show how work of this kind has been valuable in evaluating the merits of the induced polarization method, in the planning of induced polarization surveys, and in the interpretation of field data.

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