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File Created: 24-Jul-1985 by BC Geological Survey (BCGS)
Last Edit:  07-Apr-2016 by Jessica Norris (JRN)

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NMI 093A2 Mo1
BCGS Map 093A006
Status Past Producer NTS Map 093A02W
Latitude 052º 05' 48'' UTM 10 (NAD 83)
Longitude 120º 54' 27'' Northing 5773855
Easting 643334
Commodities Molybdenum, Copper, Zinc, Tungsten, Silver, Bismuth, Rhenium Deposit Types L05 : Porphyry Mo (Low F- type)
Tectonic Belt Intermontane Terrane Quesnel
Capsule Geology

The Boss Mountain deposit is situated on the eastern slopes of Big Timothy Mountain, 43 kilometres southeast of Horsefly.

The Boss Mountain molybdenum deposit is situated near the eastern margin of the Early Jurassic Takomkane batholith. The Takomkane batholith intrudes Upper Triassic Nicola Group volcanic rocks to the south and west and is in fault contact with Lower Jurassic volcanic and sedimentary rocks to the east and north. The batholith is made up of a syenodiorite phase, a granodiorite phase and a porphyritic biotite granodiorite phase. Approximately 450 metres northeast of the deposit, the porphyritic quartz monzonite Cretaceous Boss Mountain Stock intrudes the Takomkane batholith. A complex sequence of rhyolite porphyry and rhyolite dike emplacement, breccia development and molybdenum introduction is related to this intrusion.

Molybdenum mineralization is contained within quartz veins and, to a somewhat lesser extent, in breccia bodies within the granodiorite phase of the batholith. Three phases of breccia—known as phase I breccia, quartz breccia and phase III breccia—are found at the deposit. Fracturing can be grouped into eight distinct periods, with six of these being genetically related to vein formation and ore deposition. Six ore zones have been outlined at the deposit: the Main Breccia zone, the Fracture Ore zone, the South Breccia zone, the Stringer zone, the Southwest Stringer zone, and the High-Grade Vein zone.

The Main Breccia zone is composed of quartz breccia and phase III breccia with molybdenite occurring along fragment boundaries and within quartz veins cutting the breccia. The Fracture Ore zone consists of the rebrecciated upper part of the quartz breccia and adjacent overlying granodiorite in the Main Breccia zone. The matrix is composed of molybdenite with only a very minor amount of quartz. The South Breccia zone is composed of phase I and phase III breccias with ore-grade mineralization occurring erratically as pods in fractures and in the matrix. The Stringer zone is a subparallel swarm of veins around the northwest and western margins of the Main Breccia zone. The Southwest Stringer zone is a zone of subparallel veins situated approximately 300 metres south of the Main Breccia zone. This zone is at least partly bounded to the southwest by what appears to be a major fracture zone localized along an intensely altered and mineralized andesite dike. The High-Grade Vein zone is a system of quartz-molybdenite veins localized in a sheared and intensely altered andesite dike north of the Main Breccia zone.

All the ore zones are composed of more than one stage of molybdenite mineralization. Molybdenite is the only mineral of economic importance in the deposit. Pyrite is the most abundant and widespread accessory mineral, with chalcopyrite, sphalerite, scheelite, tetrahedrite, rutile, ankerite, bismuthinite, pyrolusite, magnetite, hematite and anatase also present.

Six alteration assemblages have been recognized in the deposit. Four of these are related to molybdenum mineralization and are, from oldest to youngest, 1) garnet-hornblende, 2) biotite, 3) quartz-sericite-pyrite-potassium feldspar-chlorite and 4) chlorite- talc. An epidote-chlorite assemblage had both a premineralization stage and a stage coincident with mineralization. A zeolite-calcite-clay assemblage is postmineralization.

At least two phases of molybdenite deposition occurred. Hydrothermal biotite dated at 102 million years was deposited between the two stages of molybdenum mineralization and, thus, is bracketed by the mineralization.

The Boss Mountain deposit was discovered in 1917. The following year, a small amount of selected molybdenum ore was shipped for processing. The Consolidated Mining and Smelting Company acquired the rights to the deposit in 1930, later selling the claims for taxes in 1955. Herman Huestis and Associates later acquired the claims. From 1956 to 1960, Climax Molybdenum Corporation conducted exploration programs that included mapping, geophysics, trenching and 9752 metres of diamond drilling. Noranda Mines Ltd. purchased the rights to Boss Mountain in 1961, operating until 1983, when the mine closed due to low molybdenum prices. NMC Resource Corp. currently holds a 100 per cent option on the property (

The “A” zone, situated in the centre of the mineralized breccias zones, was reported to contain an estimated 1.4 million tonnes of ore grading 0.75 per cent molybdenum disulphide in 1961 (Property File Rimfire, Sirola, 1961).

Unclassified reserves were reported as 3,838,847 tonnes grading 0.135 per cent molybdenum, including open-pit reserves reported in 1980 as 2,358,460 tonnes grading 0.11 per cent molybdenum (Noranda Mines Annual Report, 1980, 1984).

In 2011, NMC Resource Corp. sampled the country rock around and beyond the historic Noranda workings. Outcrops with visible molybdenite returned high molybdenum values, including 13.6 and 2.22 per cent molybdenum. Samples without visible molybdenite returned up to 0.069 per cent molybdenum (Press Release, NMC Resource Corporation, November 17, 2011).

In 2014, NMC Resource Corp. drilled 11 holes (3075 metres), a program designed to confirm the previously reported mineralization, extend the boundaries of the known zones at depth and along strike, and to test other potential elements in the deposit. Molybdenum mineralization, reported in all 11 drill holes, is associated with quartz veins up to 30 centimetres wide. The quartz veins contain up to 5 per cent coarsely disseminated molybdenite and trace pyrite. Preliminary results indicate that rhenium mineralization is closely associated with molybdenum in these vein sets. The host rock is a variably brecciated granodiorite with localized regions of potassic and argillic alteration within the mineralized zones. Drilling has demonstrated molybdenum mineralization at least 180 metres beyond previously tested depths, as well as further along strike. Assay results also successfully demonstrated the potential for rhenium mineralization, which had not been previously assayed for (Assessment Report 35522).

Highlights of assay results include: 0.14 per cent molybdenum over 181.50 metres (drill hole BOSS-14-01); 0.14 per cent molybdenum over 46.75 metres and up to 3.66 grams per tonne rhenium over 0.75 metre (drill hole BOSS-14-03); 0.082 per cent molybdenum over 259.00 metres and up to 1.29 grams per tonnes rhenium over 0.50 metre (drill hole BOSS-14-06); 0.17 per cent molybdenum over 22.00 metres (drill hole BOSS-14-10); and 0.13 per cent molybdenum over 397.75 metres and up to 4.25 grams per tonne rhenium over 0.70 metre (Drill hole BOSS-14-11) (NMC Resource Corp. Press Releases November through December 2014).

EMPR AR 1915-K58; 1917-F134; 1918-K147; 1929-C229; 1930-A198, 131-A111; 1956-34; *1957-18; 1958-15; 1959-24; 1961-21; 1962-20; 1963-39; *1964-65; 1965-141; 1966-133; 1967-125; 1968-152; 1969-178; 1970-210; 1971-129; 1972-329; 1973-287; 1974-234
EMPR ASS RPT 5821, 6081, *35522
EMPR BULL *9, p. 34
EMPR MAP 65 (1989)
EMPR MINING 1975-1980, Vol.1, p. 3; 1981-1985
EMPR OF 1992-1; 1998-8-F, pp. 1-60
EMPR PF (*Stevenson, J.S. (1942): Report on the Boss Mountain Molybdenite Prospect; Field Sketch of Drilling and sections on Boss Mountain Molybdenite, Sept. 1942; Plan showing geology and drill holes, sections and transcript of field notes, Boss Mountain, Oct. 1942; Drill Plan, Southwest Potash Corp. Boss Mountain Project, Feb. 1959; Computation of Average Grade of ore from Drill hole assays Apr. 1961; GSC Map Fig. 20 from Economic Geology 20, 1962; Air Photos, 1962; The Ore-Forming Sequence - Boss Mountain Mine, abstract from unknown source; M.E.G. Meeting Feb.11, 1964, Boss Mountain Molybdenum Property; Boss Mountain excerpt from unknown source; Heim, R.C. and Burton, A.D.K. Oct. 1965, Boss Mountain Mine Geology; Eastwood, G.E.P. Nov. 1964, Report on Boss Mountain Mine (also field notes and maps); Deputy Minister of Mines Correspondence 1939-1943 regarding Big Timothy Mountain deposit; Claim Map April 1967, Boss Mountain Area; Brynnor Mines Ltd. Aug. 1969, Status clipping; Brynnor Mines Ltd. 5045 Level plans; Brand, M.A. Apr.1974, Boss Moutain Pit Project; Rohwedder, J., Grove, E.W. Mar. 1975, Boss Mountain Project; Grove, E.W. Mar.1975, Boss Mountain Mine Open Pit Proposal; Smith, J.B. May 1975, Boss Mountain Expansion Project, Organization, Practices and Procedures; Reports Submitted to B.C. Department of Mines and Petroleum Resources on the Boss Mountain Mine Feb. 21, 1975)
EMPR PF Rimfire (Sirola (1961): Report - Boss Mountain Molybdenite Property; Sirola (1961): Memos re: Boss Mountain Molybdenite Property)
EMR MIN BULL MR 166; 223 B.C. 200
EMR MP CORPFILE (Consolidated Mining and Smelting Co. Ltd.; Noranda Mines Ltd.)
EMR MP RESFILE (Boss Mountain Mine)
GSC EC GEOL *20, p. 246; *70, No.1, p. 4 (Soregaroli, A.E. (1975): Geology and Genesis of the Boss Mountain Molybdenum Deposit, British Columbia)
GSC MEM 118, p. 91
GSC OF 6157
CANMET RPT 592 (1925), p. 32
CIM Special Volume *15, p. 432 (Soregaroli, A.E. and Nelson, W.I., 1976); Vol.61, No.679, p. 1331 (White, W.H., Harakal, J.E. and Carter, N.C. 1968)
GCNL #79, 1969; #121, 1976; #56, 1979; #42, 1982; #200, 1983
N MINER June 24, 1976; Jan.15, 1981
W MINER Vol.37, No.12, p. 27 (1964); Feb. 1979; Dec. 1982; Feb.,Nov. 1983; Apr. 1984
*Soregaroli, A.E. (1968): Geology of the Boss Mountain Mine, British Columbia, Ph.D. Thesis, University of British Columbia
World Mining Sept. 1975, p. 80
PR REL NMC Resource Corp., Nov. 17, 2011; Oct. 14, 2014; *Nov. 6, 2014; *Nov. 17, 2014; *Dec 2, 2014