Open AccessIndicator minerals in fine-fraction till heavy-mineral concentrates determined by automated mineral analysis: examples from two Canadian polymetallic base-metal deposits
Author(s) -
H D Lougheed,
M B McClenaghan,
Daniel LaytonMatthews,
M I Leybourne
Publication year - 2022
Language(s) - English
Resource type - Reports
DOI - 10.4095/328011
Subject(s) - mineral , geology , heavy mineral , mineralogy , geochemistry , gangue , sulfide minerals , chemistry , pyrite , provenance , organic chemistry
Exploration under glacial sediment cover is a necessary part of modern mineral exploration in Canada. Traditional indicator methods use visual examination to identify mineral grains in the 250 to 2000 µm fraction of till heavy-mineral concentrates (HMC).This study tests automated mineralogical methods using scanning electron microscopy to identify indicator minerals in the fine (<250 µm) HMC fraction of till. Automated mineralogy of polished grains from the fine HMC enables rapid data collection (10 000-300 000 grains/sample).Samples collected near two deposits were used to test this method: four from the upper-amphibolite facies Izok Lake volcanogenic massive-sulfide deposit, Nunavut, and five from the Sisson granite-hosted W-Mo deposit, New Brunswick.The less than 250 µm HMC fraction of till samples collected down ice of each deposit contain ore and alteration minerals typical of their deposit type. Sulfide minerals occur mainly as inclusions in oxidation-resistant minerals, including minerals previously identified in each deposit'smetamorphic alteration halo, and are found to occur farther down ice than the grains identified visually in the greater than 250 µm HMC fraction. This project's workflow expands the detectable footprint for certain indicator minerals and enhances the information that can be collected from tillsamples.