The earliest known structural event in the region resulted in isoclinal folding of Keewatin volcanics and interflow sediments during the Kenoran Orogeny, 2.5 billion years ago (Jambor 1971). Precambrian age faults, fractures, and joints observed within the mine area exhibit variable dips.
Regional faults occur as prominent north- to northwest structures which extend for hundreds of kilometres and weak northeast-trending sets (Andrews et al. 1986). Many smaller faults are present locally and are likely related to these large-scale fault systems. The major faults are believed to have been active in the late Archean; before, during, and after Huronian sedimentation; and during and after intrusion of the Nipissing diabase emplacement (Andrews et al. 1986). Post-diabase tectonic activity is considered a possible mechanism for creation of the structures hosting the silver-cobalt vein systems in the Cobalt Camp (Andrews et al. 1986).
Alteration mineral assemblages and styles present suggests that a large-scale, albeit weak, hydrothermal system (or systems) was in effect: silica, chlorite, and carbonate are the most observed alteration minerals throughout the area drilled. Chlorite ± silica ± carbonate preferentially alter drilled mafic volcanic rocks. Chlorite ± iron oxide (hematite) preferentially alters the conglomerate.
Fault and structurally related alteration effects are also present: rocks altered moderately to intensely by clay minerals, sericite, and carbonate are found spatially associated with broken, rubbly, and sometimes gougey core.
Based on the observations made throughout the multiple drilling programs, alteration minerals observed, which directly correlate with high-grade mineralization, are restricted to carbonate, calcite and chlorite, as well as base-metal sulphide minerals. These are also the known alteration assemblages and characteristics defining the Cobalt Mining District.
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.
High-grade silver mineralization occurs as steeply-dipping veins within any of the three main rock types: Archean Keewatin volcanics, Coleman Member sediments and Nipissing diabase.
Archean Keewatin volcanics: These rocks comprise both metavolcanics and metasediments. The volcanics are most commonly intermediate to mafic pillowed basalt and massive flows. Between flows, deep-water cherty sediments and pyroclastic rocks were deposited. These interflow sediments are commonly rich in pyrite, pyrrhotite, chalcopyrite, galena, and sphalerite. Throughout the area, the volcanics are intruded by various mafic and ultra-mafic dykes.
Algoman intrusive: A large hornblende syenite pluton intruding the mine property has potential for gold mineralization but is underexplored to date.
Proterozoic Huronian Supergroup: Huronian rocks comprise the majority of exposed outcrop on the Langis property and consist of gently-dipping, unaltered clastic, glacially-derived sediments unconformably overlying the older Keewatin volcanic and intrusive rocks (Lowes, 1963). These sediments form the Coleman Member of the Gowganda Formation and consist of para- and ortho-conglomerates, pebbly sandstone and greywacke, and thinly-bedded argillites.
Early Proterozoic (Keewenawan): Rocks of this age are represented by the Nipissing diabase sill, a prominent and important rock type in the Cobalt Basin. The diabase intrudes in the form of extensive sheets as well as less prominent dykes and plugs.
Historically, the Langis Mine produced over 10.4 Moz Ag with a recovered grade of approximately 25 oz/t from shallow depths, and 358,340 lbs of cobalt.
Historically, the Hudson Bay Mine produced 6.4 Moz Ag at 123 oz/t, and 185,570 lbs of cobalt from 58,000 tons.
The Langis and the Hudson Bay Projects do not currently contain any mineral resources or mineral reserves.
The Cobalt Mining District has produced over 600 Million oz Ag and 28 Million lbs Co (Joyce et al. 2012). One reported mine working from the Cobalt Camp reached 255,146 g/t Ag (or 9,000 oz/t Ag) over 0.36 metres. This single stope at the 30 m level on this vein produced 4.5 Moz Ag.
Silver was discovered at Cobalt in 1903 during the construction of the Timiskaming and Northern Ontario Railway from North Bay to develop the agricultural land in the New Liskeard area. Fred LaRose, a blacksmith employed in the construction of the railway, is credited with the first discovery, but the first application for claims, filed on August 13, 1903, was made by J.H. McKinley and E.F. Darragh, subcontractors who supplied ties for the railroad. They found silver-bearing float at the south end of Cobalt Lake. The first assay results showed bismuth but no silver. McKinley subsequently sent the ore for assay to McGill University and was informed by Dr. Milton Hersey of Montreal that the ore contained 4,000 ounces of silver per ton. Dr. Willet G. Miller, Ontario’s first provincial geologist, visited the area in November 1903 and found that four veins had been located, three very rich in silver. In addition, Tom Hebert had staked the property that later became the Nipissing Mine. Dr. Miller reported the news through an article in the Mining Journal of New York and through an Ontario Bureau of Mines publication. The final discovery in 1903 was made by Neil King who staked the property on which the O’Brien mine was to rise in 1906 and to continue production without a break until 1966 (Zoldy 2006).
Mr. Gary R. Thompson, P.Geo., Chairman, President and CEO of Brixton, is the QP who approved the scientific and technical information on this website. Reported drill results are drilled intervals and true widths have not been determine at this time.
