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Trace elements distribution in colloform chalcopyrite and tennantite: insights from Butte (USA) and Lisheen (Ireland)

Published inGeochimica et cosmochimica acta, vol. 427, p. 156-176
Publication date2026-08
Abstract

Sulfides and sulfosalts in base-metal (Cu, Pb, Zn) deposits are significant reservoirs for trace elements, providing critical insights into ore genesis. Despite several studies in the literature on euhedral chalcopyrite and tennantite, their colloform equivalents, commonly consisting of mixtures of euhedral and acicular crystals, remain largely understudied from a geochemical perspective. This study investigates the micro- to nanoscale composition and distribution of trace-elements in colloform chalcopyrite and tennantite from two distinct hydrothermal environments: the Cordilleran lodes of Butte (Leonard mine; USA) and the low-temperature stratabound Zn-Pb deposit of Lisheen (Ireland). At both localities, chalcopyrite and tennantite are significantly enriched in Ge, Ga, Ag, and Pb (up to several 1000 s ppm), with zonal distributions at the microscale. However, the mode of occurrence differs in the two deposits. At Butte, Ge, Ga, Ag, Pb, and Tl are mainly incorporated into the crystal structure of euhedral grains, with Ge showing a positive correlation with Ga, Pb and Tl. While at Lisheen, Ge, Ag, and Pb are concentrated in thin colloform bands, further nanoscale investigations reveal that Ge is hosted within numerous nanoscale renierite inclusions (ideal formula = [(Cu,Zn)11(Ge,As)2Fe4S16]), rather than the acicular tennantite crystal structure (< 50 ppm Ge). These inclusions are cogenetic with micro- to nanoscale size fluid inclusions enriched in H2O, K, and Ca. In this case, these nanoscale renierite inclusions are interpreted to have formed either through exsolution or through the entrapment of a dense liquid under high levels of fluid supersaturation. In both case studies, acicular chalcopyrite exhibits a distinct <110> crystallographic preferred orientations (CPO) with a girdle on {001}. Acicular textures in both tennantite and chalcopyrite are consistently depleted in trace elements (Ge, Ga, Ag, Pb; <50 ppm). We suggest that the spatial distribution of trace elements is strongly influenced by a complex variety of parameters such as fluid composition, precipitation conditions (temperature, pH, supersaturation, growth kinetics). These results demonstrate that euhedral chalcopyrite and tennantite from high to intermediate sulfidation assemblages in magmatic-hydrothermal and sedimentary-hosted systems can host significant Ge and Ga concentrations. Detailed multiscale examination of sulfide microtextures is critical for interpreting the complex chemical zoning, potentially resulting in a better understanding of ore-forming processes.

Funding
  • European Commission - Enhanced X(cross)-disciplinary Community-driven Imaging Technologies for Earth and Environmental material research [101131765]
Citation (ISO format)
CUGERONE, Alexandre et al. Trace elements distribution in colloform chalcopyrite and tennantite: insights from Butte (USA) and Lisheen (Ireland). In: Geochimica et cosmochimica acta, 2026, vol. 427, p. 156–176. doi: 10.1016/j.gca.2026.06.006
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Article (Published version)
Identifiers
Journal ISSN0016-7037
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