Mineralization at the Langis project consists of high-grade silver-cobalt assemblages, and moderate to high-grade base-metal sulphide assemblages.
Medium- to fine-grained sulphides are hosted in carbonate ± chlorite ± hematite ± quartz veins, and with ± silver ± cobalt mineralization. Cobaltite, smaltite and other silver arsenides in the form of mm- to cm-scale veins and veinlets are hosted within various rock types and make up the high-grade mineralization style. Silver arsenides also occur interstitially and finely disseminated adjacent to coarser or thicker veins of cobaltite. Where observed, cobaltite is generally coarse-grained and intergrown with finer silver and nickeline; native silver occurs as flaky fracture coatings and as hairline stingers near other mineralization. Nickeline is rarely observed, but most frequently in association with carbonate veins.
A base metal sulphide assemblage makes up a significant proportion of the mineralization intersected at Langis, and consists of pyrite, sphalerite, chalcopyrite, and rarely galena, pyrrhotite, and marcasite. Sulphides occur generally as fine- to medium-grained disseminations in host lithology, and as mm- to cm-scale veinlets and veins, often associated with carbonate ± quartz veins. Chalcopyrite, pyrite, and rarely sphalerite also occur as disseminations in clasts in volcanic and sedimentary rocks, and as coarser grains when in association with carbonate veins, particularly with vuggy calcite veins. Sphalerite most often occurs spatially associated with fault zones in medium- to coarse-grained agglomerations. Galena occurs most frequently in association with carbonate veining. In graphitic schist chalcopyrite, pyrite and some pyrrhotite are observed locally as pods, or coarse-grained disseminations.
Owsiacki (1988) indicates “significant high‐grade silver intersections have been recovered from within all three rock types being Nipissing Diabase, Coleman sediments, and, Archean volcanics at the western margin of this trough. One of the best assays to date is 50 ounces over 9.45 m, intersected in the volcanic rocks.”
The most important ore mineral is native silver and secondary metals are cobalt, nickel and copper. All silver-bearing veins in the Langis Mine area are steeply dipping and are categorized as either single-vein or multiple-vein type structures (Jerome, 1969).