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File Created: 24-Jul-1985 by BC Geological Survey (BCGS)
Last Edit:  27-Nov-2014 by Laura deGroot (LDG)

Summary Help Help

NMI 093K9 Hg1
Name PINCHI LAKE MERCURY, PINCHI, CHIEF, DUGOUT Mining Division Omineca
BCGS Map 093K068
Status Past Producer NTS Map 093K09W
Latitude 054º 37' 58'' UTM 10 (NAD 83)
Longitude 124º 26' 14'' Northing 6054877
Easting 407228
Commodities Mercury Deposit Types E01 : Almaden Hg
I08 : Silica-Hg carbonate
Tectonic Belt Intermontane Terrane Cache Creek
Capsule Geology

The Pinchi Lake mercury mine is located on a prominent limestone hill on the north shore of Pinchi Lake about 25 kilometres from Fort St. James.

The deposit was discovered in 1937 by J.G. Gray of the Geological Survey of Canada. The area was staked in 1938 by A.J. Ostrem and optioned to Cominco. Production first occurred in 1940 with peak production in 1943. Due to the falling price of mercury production ceased in 1944. The mine was reopened in 1968 and operated until 1975 when mercury prices declined.

The deposit is associated with the Pinchi fault which separates Carboniferous-Jurassic Cache Creek Complex (Group) rocks from Upper Triassic Takla Group rocks. Cache Creek Complex rocks which in the area consist of ribbon chert, quartzite, schist, limestone and minor greenstone, all of which have a general northwesterly strike and a steep northeasterly dip. Small bodies of serpentinite intrude the Cache Creek rocks. A number of faults, mostly with a northwesterly trend, occur in the Pinchi fault zone.

Cinnabar mineralization is concentrated in breccia zones along the faults as well as in strata cut by the faults. Known orebodies roughly parallel the bedding and occur mainly in dolomitized limestone beneath bands of impervious schist although some ore is also found in the quartz-carbonate-mica schists. Most of the cinnabar occurs as veinlets and blebs filling pre-existing openings such as fissures, solution cavities and interstices between grains and breccia fragments. The cinnabar is mainly a massive red variety but there is also some bright red earthy cinnabar as well as some crystallized cinnabar. A little stibnite and scattered grains of pyrite have been found.

The south fault, which hosts most of the mineralization, strikes about 320 degrees and dips about 60 degrees west. The faulting style changes from one distinct fault to a group of closely spaced faults 300 metres to the northwest.

Possible resources are 1.1 million tonnes grading 3.2 kilograms per tonne mercury (Cominco Ltd. Annual Report 1992).

Bibliography
EMPR AR 1939-99; 1940-85; 1941-79; 1942-75; 1943-76; 1944-42,75;
1965-112; 1967-117; 1968-145-147
EMPR BULL *5, pp. 18-33
EMPR EXPL 1992-69-106
EMPR FIELDWORK 1992, pp. 475-482
EMPR GEM 1969-156; 1970-117; 1971-167; 1972-364; 1973-333; 1974-254
EMPR MIN POT MAP 1993-2
EMPR MAP 65 (1989)
EMPR OF 1992-1; 1993-9
EMPR PF (Mercury Deposits - Mercury group, unknown author and date; Description of Deposits - Pinchi Lake, unknown author and date; Lode Deposits - Deposits Related to Major Fault or Shear Zones - Pinchi Fault Zone, unknown author and date; Cominco Ltd. (unknown): Fig. 1 - Workings on the Pinchi Lake Cinnabar Property; Cominco Ltd. (unknown): Pinchi Lake Cinnabar Property (larger version of document 258 / Fig. 1); Eardley-Wilmot, V.L. (1938): Mercury - Pinchi Lake; Stevenson, J.S. (1939): Preliminary Report on Pinchi Lake Cinnabar Showings; unknown (1939-10-15): Geological Plan Map - Mercury Mine; Armstrong (1942): Regional Geology Map; Cominco Ltd. (1943-09-01): Pinchi Lake Hg - Map Section 43; unknown (1950-02-28): Mercury at Pinchi Lake; unknown (1968): Pinchi Lake Mine Photos of ore bin and processing plant (Front) (Back); unknown (1966): Air Photos - 66 - 34, 66 - 35, 66 - 36, 66 - 37, 66 - 38, 66 - 41, 66 - 42, 66 - 43, 66 - 44, 66 - 45, 66 - 46, 66 - 47; unknown (1972-07-18): Airphoto Index Map; Cominco Ltd. (1974-09-28): Mineral Industries In Western Canada - The Pinch Lake Mine; Correspondence to Minister of Mines, 1974; Craft, H.W. (1974-02-28): Re: Description of Deposits - Pinchi Lake; Cominco Ltd. (1974-09-28): Mineral Industries In Western Canada - The Pinchi Lake Mine; Cominco Ltd. (1989-02-10): Annual Report 1988; Prospectors Report 2000-4 by William Welsh)
EMR MP CORPFILE (Cominco Ltd.)
EMR MR MIN BULL 223 B.C. 225
GSC MAP 630A; 907A; 971A; 1424A; 1582G
GSC MEM *252, pp. 166-171
GSC OF 2593, 2846
GSC P 38-14, p. 9; 42-11, p. 12-15; 90-1F, pp. 115-120; 91-1A,
pp. 7-13
CIM Transactions, pp. 311-323 (Armstrong, J.E., (1942): Geology of
the Pinchi Lake Mercury Belt, British Columbia); Vol. 48, pp.
13-26 (Bainbridge, R., (1945): Pinchi Lake Mercury Reduction
Plant)
CJES Vol.14, No.6, Jun., 1977, pp. 1324-1342 (Paterson, I.A., (1977):
The Geology and Evolution of the Pinchi Fault Zone at Pinchi Lake,
Central B.C.

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