b'Chalcocite conductivityFeatureFigure 2.A cross plot of EM conductivity against inferred solid grain density (porosity removed). For each of categories I to V (#114), chalcocite content increases from left to right as density increases. Category VII a host siltstone, with minor pyrite and graphite, plots below 1 S/m. In categories I to V conductivity increases with density, and more or less trends to a value of ~1800 S/m at nominal density 5.65 g/cc for chalcocite, near Telkes T2. For the fine grained dark massive chalcocite, chalcopyrite is seen to boost conductivity as does graphite (IV), but pyrite diminishes conductivity (V). Heavily pyritic samples VI (#1520) have low conductivity. By way of comparison, typical values (encountered by the writer) for massive graphite (Sydney Basin cindered coal), chalcopyrite ores (Cobar NSW), pyrrhotite nickel ores (Kambalda WA), and pyrite (various; see Emerson, 2019) are shown. This limited evidence seems to suggest that chalcocite in massive aggregates is a fairly good connector / threader conductor intermediate between chalcopyrite and pyrite.for porosity (up to 47%) recorded for the fine grained massivepyrite (Group V). Also, metasedimentary host rock content granular samples #621 embracing categories II to VII. This isdiminishes as sulphide content increases. Chalcopyrite and consistent with the mode of genesis. The porosity for #1 (7%) isgraphite appear to boost fine grained, massive chalcocite due to fracturing and intergranular voids. The chief interest inore conductivity, pyrite seems to lower it. This is a plausible this work is how well the solid materials conduct and, especially,result given the conductivity and nature of both graphite how good a conductor is chalcocite. To this end, conductivityand chalcopyrite: very good conductors with a threading / was plotted against inferred solid grain density (porosityconnecting habit; compared to pyrite which, in aggregate, removed). Conductivity plotted against porosity, or wet, oris often a moderate, not very well-connected conductor dry density was not particularly informative. Although, clearly,(Emerson, 2019). Samples #35 in Group II diminish in porosity development cannot help conductivity it seems that,conductivity as density decreases owing to increasing amounts except for the pyritic dominant Group VI and the host VII, theof metasedimentary host rock. The pyrites in Group VI are poor solid framework of the mineral assemblage is well networkedconductors. They are altered, most of them are disaggregating by the conducting elements i.e., sulphides of copper, and(sugar pyrite), and chalcocite content is low.graphite. The results here are for mineral aggregates i.e., ores, not single crystals. However, single (presumed) crystal dataA pure chalcocite aggregate (#1, Group I) has a conductivity from the sparse literature are included for reference: Harveyssimilar to TelkesT2 i.e. ~1800 S/m. To which samples #35,(1928), measured by galvanic microprobe arrays (fractions914 trend as density increases. This value of 1800 S/m appears of mm Wenner electrode spacings); and Telkes (1950), by ato be indicative, but by no means definitive, of very high copper technique that is not clear in her paper. Also included in Figuregrade chalcocite ore. Until further data becomes available it 2, for comparison, are typical values, encountered by the writer,seems reasonable to regard chalcocite as a good conductor, for deposits of commonly encountered sulphides (pyrite,probably with good connectivity (noted by Shuey, 1975), chalcopyrite, pyrrhotite) and graphite. ranking below chalcopyrite and above pyrite in conductivity.Discussion Concluding remarksIn Figure 2, generally, conductivity increases to moderate levelsChalcocite manifests a good, but not excellent, mesoscale as density increases to chalcocites nominal value of 5.65 g/cc.conductivity at least for the samples in this limited test. More This trend in conductivity at lower densities is not due toneeds to be done not only on chalcocite, but on the chalcocite chalcocite alone as there are contributions from chalcopyritefamily, which includes the little studied, copper deficient and minor graphite (Group III) graphite and pyrite (Group IV),variants: digenite Cu 9 S 5(78.1% Cu), djurleite Cu 31 S 16(79.4% Cu), JUNE 2021 PREVIEW 50'