Research Article| September 01, 2018 White Mica Geochemistry of the Copper Cliff Porphyry Cu Deposit: Insights from a Vectoring Tool Applied to Exploration Camilo Uribe-Mogollon; Camilo Uribe-Mogollon The New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801, USA †Corresponding author: e-mail, camilo.uribe@student.nmt.edu Search for other works by this author on: GSW Google Scholar Kierran Maher Kierran Maher The New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801, USA Search for other works by this author on: GSW Google Scholar Economic Geology (2018) 113 (6): 1269–1295. https://doi.org/10.5382/econgeo.2018.4591 Article history accepted: 27 Jul 2018 first online: 23 Oct 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Camilo Uribe-Mogollon, Kierran Maher; White Mica Geochemistry of the Copper Cliff Porphyry Cu Deposit: Insights from a Vectoring Tool Applied to Exploration. Economic Geology 2018;; 113 (6): 1269–1295. doi: https://doi.org/10.5382/econgeo.2018.4591 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyEconomic Geology Search Advanced Search Abstract The Copper Cliff porphyry copper prospect, located 48 km east-southeast from Missoula, Montana, presents two distinct phyllic alteration events: an early green-colored expression, locally texturally destructive and associated with specular hematite and hypogene copper mineralization, and a later white variety generally structurally controlled and associated with pyrite. Variations in the mineral chemistry of white micas were evaluated by short-wave infrared spectroscopy, electron microprobe analysis, and laser ablation-inductively coupled plasmamass spectrometry (LA-ICP-MS). The analytical results allow the identification of a systematic compositional variation of the white micas, possibly controlled by redox changes in the system. The early green phyllic expression consists of Fe-bearing white micas characterized by longer Al-OH absorption wavelength (2,206–2,210 nm) and formed by oxidized magmatic fluids, whereas the late white phyllic phase contains white micas enriched in V and Sc with shorter Al-OH absorption wavelengths (2,197–2,206 nm) formed under less oxidizing conditions. Based on LA-ICP-MS trace element analyses of white micas, Cu concentrations decrease exponentially with distance from the porphyry center, in contrast to Zn, which tends to increase. The application of the Cu/Zn ratio of white micas in a manner analogous to the chlorite proximitor equation of Wilkinson et al. (2015) allows the estimation to the center of the hydrothermal system within a radial distance of approximately 710 m in samples of the early green phyllic alteration phase and within approximately 1,300 m in samples of the late white phyllic alteration style. Therefore, the Cu/Zn ratio in white micas at Copper Cliff deposit may provide a useful tool for targeting the hydrothermal center. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.