3. The Search for Massive Sulfides

Pyrite – the firestone

“…The mass property, magnetic susceptibility, and EM conductivity data are given in Table 3. Ward (1966) defines a massive sulphide as being at least 50% by volume sulphides and having a minimum density of 3.8 g/cc. However, for this 36 sample data set it is deemed preferable to classify the 25 samples with air dried bulk densities exceeding 4.2g/cc as massive, the five samples (#28-31, 35) with densities in the 3.7-4.0 g/cc range as semi massive, and the remaining six samples (#25-27, 32-34) in the 2.7-3.3 g/cc range as low density pyrite rock.…”

Preliminary compilation of descriptive geoenvironmental mineral deposit models

“…Most massive sulfide replacement bodies have high density, low resistivity, are electrically chargeable when excited by induced polarization, have high magnetic susceptibility when magnetite or pyrrhotite are present, and may generate negative self-potential voltages (Ward, 1966;Buselli, 1980;Frischknecht and others, 1991;FallonandBusuttil, 1992;Thomas and others, 1992). Consequently, these deposits often can be identified by detailed electrical, gravity, magnetic, and self-potential surveys.…”

“…Specifics of particular geophysical responses are controlled by sulfide mineralogy, concentration, and continuity; hydrologic conditions; and by host and country rock characteristics and geometry. Airborne or ground-based electromagnetic, direct current resistivity, and induced polarization surveys can identify low-resistivity and chargeable sulfide masses, high-resistivity silicified-carbonitized zones, and pyritic alteration assemblages (Ward, 1966;Zonge and Hughes, 1991;Shalley and Harvey, 1992;Thomas and others, 1992). Anomalies initially identified by airborne electromagnetic and magnetic surveys can be further studied by groundbased geophysical surveys coupled with geologic and geochemical investigations.…”