ChalcopyriteChalcopyrite (CuFeS2) is a common copper oreCopper ore mineral that displays variable but often poor leachingLeaching behavior under typical heap leachHeap leach conditions. Ongoing research has provided inconsistent magnitudes of activation energy and dissolutionDissolution mechanisms, even for chalcopyriteChalcopyrite leached in the same chemical systems. This is possibly due to variations in crystallography, impuritiesImpurity such as Zn, Ag, Co, and Se, which natural chalcopyriteChalcopyrite readily accommodates, or interference from additional sulfidesSulfide, like cubanite, haycockite, mooihoekite, putoranite, or talnakhite, which have similar crystallographic signatures and optical properties. Additional contributors to these observations are unconstrained variations in chalcopyriteChalcopyrite semiconducting properties, such as charge carrier type, density, and resistivityResistivity. Little is known about these in natural chalcopyritesChalcopyrite. Currently, most natural chalcopyritesChalcopyrite are considered n-type semiconductorsSemiconductors, while an estimated 3–5% of the species are weak to moderate p-type; measured resistivitiesResistivity reported in the literature range from 10 −5 to 150 Ω-cm. However, measurements of natural samples are uncommon and typically uncorrelated with composition. Previous attempts to correlate chalcopyriteChalcopyrite composition and semiconducting properties have yielded ambiguous results, largely due to limited numbers of samples and limited methods of characterization. This paper reports preliminary results from an ongoing study of the relationship between chalcopyriteChalcopyrite composition and semiconducting properties. The results shown are based on 9 whole-rock chalcopyriteChalcopyrite samples, characterized by electron microprobe and four-probe station for sample composition, resistivityResistivity, charge carrier density, and resistivityResistivity. These natural rock samples were found to have averages of 4.11 Ω-cm resistivityResistivity (median 0.35 Ω-cm) and mobility of 15.09 cm2/V-sec (median 8.95 cm2/V-sec). These preliminary results show a potential inverse correlation between chalcopyriteChalcopyrite Ag concentration and charge mobility, while other elementsElements cover a wide range with no clear effects. This may be due to the effect of fine-scale non-chalcopyriteChalcopyrite sulfideSulfide impuritiesImpurity in the samples, which affect the semiconducting properties, but not mineral composition measurements.