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File Created: 24-Jul-1985 by BC Geological Survey (BCGS)
Last Edit:  25-Feb-1991 by Robert G. Gaba (RGG)

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NMI 092J15 Au18
BCGS Map 092J087
Status Past Producer NTS Map 092J15E, 092J15W
Latitude 050º 53' 55'' UTM 10 (NAD 83)
Longitude 122º 45' 05'' Northing 5638580
Easting 517483
Commodities Gold, Silver, Copper, Lead, Zinc Deposit Types I09 : Stibnite veins and disseminations
Tectonic Belt Coast Crystalline Terrane Bridge River
Capsule Geology

The Minto polymetallic veins are on the north side of Carpenter Lake, 1.7 kilometres northeast of the mouth of Gun Creek.

The property is underlain by northwest trending argillites, cherty quartzites, ribbon cherts and volcanics of the Mississippian to Jurassic Bridge River complex. Upper Cretaceous dykes of feld- spar porphyry, andesite porphyry, felsite and microdiorite cut north to northwest across the sediments, dipping steeply. Mineralization occurs in shear zones following the intrusive contact of porphyry dykes or the stratigraphic contact between sediments and volcanics. The strata, dykes and veins are offset by late strike-slip faults. The principal ore shoot occurs in cherty quartzites in a strong shear which follows, in part, along the footwall of a 6-metre wide, altered, fine-grained feldspar porphyry dyke (the "Minto dyke"). Veins up to 1.2 metres wide contain lenses and narrow bands of quartz, calcite and ankerite with coarsely crystalline arsenopyrite, pyrite, sphalerite, stibnite, pyrrhotite, galena, chalcopyrite and rare tetrahedrite, jamesonite, bismuth and gold.

Vein material generally has a banded structure defined by alternating metallic mineral concentrations and quartz-carbonate gangue. The vein also contains fragments of altered wallrock. Wallrock alteration is characterized by rare to abundant ankerite and calcite with lesser chlorite, sericite and mariposite.

The fissure, or zone of shearing, continues away from the dyke, but mineralization becomes irregular and weaker. Immediately west of the sediments, the fissure enters greenstone which is leached, carbonatized and slightly mineralized. Northeast and east of the main Minto orebody, within 500 metres, are other zones of mineralization: the Ponderosa zone is a wide area of mineralized cherts carrying small arsenopyrite-pyrite veins and lenses; the Rainbow zone is a 200 metre long narrow shear with stibnite, arsenopyrite and pyrite veins; and the Winter zone where an old (1934) adit explored galena-sphalerite-stibnite-arsenopyrite-pyrite veins in a narrow 200 metres long shear. The best recent assay, obtained from the Rainbow zone, graded 7.78 grams gold per tonne over 1.0 metre and 3.5 grams silver per tonne over 1.5 metres (Assessment Report 14740). The Minto mine was in operation from 1934 to 1940 during which time over 2130 metres of underground work was done, and a total of 80,650 tonnes of ore grading 6.8 grams gold and 19.9 grams silver per tonne was produced. The mine yielded 546 kilograms gold, 1,573 kilograms silver, 9,673 kilograms copper and 56,435 kilograms lead.

EMPR AR 1930-202; 1931-113; 1932-217; 1933-270; 1935-A29; *1936-F3; 1941-57; 1944-A56; 1945-A88
EMPR ASS RPT 5364, 5792, 13870, *14740, 16964, 17790
EMPR EXPL 1985-C217; 1988-C122
EMPR FIELDWORK 1974, p. 38; 1985, pp. 303-310; 1986, pp. 23-29; 1987, pp. 93-130; 1988, pp. 115-152; 1989, pp. 45-72; 1990, pp. 75-83
EMPR GEOLOGY *1975, pp. 57-63
EMPR Inspections Branch File #61026
EMPR OF 1987-11; 1988-3; 1989-4; 1990-10
EMPR PF (Report by D.E. Pearson 1974; Map, underground sampling, 1934; Statement of Material Facts, Avino Mines and Resources, August 1, 1991; Plan map of drillholes and geology of North zone, 1988; Undeground and surface plan maps of Minto mine)
GSC OF 482
GSC P 43-15, 73-17
CANMET IR #748, pp. 61-71 (1934); #771, 1935; #776, 1936; #785, 1937
CJES 1987, Vol. 24, pp. 2279-2291
ECON GEOL 1989, 84, pp. 2226-2236
GCNL #25(Feb.5), 1985
NAGMIN March 1, 1985
Sebert, C.F.B. (1987): Description of 22 Mineral Properties, Bridge River Mining Camp, Unpublished B.Sc. Thesis, University of British Columbia