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File Created: 24-Jul-1985 by BC Geological Survey (BCGS)
Last Edit:  18-Apr-2011 by Larry Jones (LDJ)

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NMI 092O2 Cu1
BCGS Map 092O017
Status Developed Prospect NTS Map 092O02E
Latitude 051º 08' 00'' UTM 10 (NAD 83)
Longitude 122º 36' 51'' Northing 5664723
Easting 526996
Commodities Copper, Gold, Molybdenum, Silver Deposit Types L04 : Porphyry Cu +/- Mo +/- Au
Tectonic Belt Intermontane Terrane Methow, Overlap Assemblage
Capsule Geology

The Poison Mountain porphyry copper deposit is on the southwest flank of Poison Mountain, 37 kilometres west of the Big Bar cable ferry on the Fraser River.

Mineralization at Poison Mountain is associated with two granodiorite to quartz diorite stocks (the Main and North porphyries) which intrude arkosic sandstones, conglomeratic sandstones and shales of the Lower Cretaceous Jackass Mountain Group. The stocks comprise relatively unaltered cores of hornblende-plagioclase porphyry which grade outwards into biotite-plagioclase porphyry in which the biotite is an alteration product of hornblende. The intrusion, potassic alteration and mineralization at Poison Mountain are about 59 to 56 Ma in age (Paleocene) as indicated by potassium-argon dating of hornblende and biotites from the mineralized system (Canadian Institute of Mining and Metallurgy Special Volume 15).

The highest grade mineralization occurs within the biotite-altered border phases of the intrusions and adjacent biotite- hornfelsed sedimentary rocks. It consists mainly of pyrite, chalcopyrite, molybdenite and bornite, which occur as disseminations and fracture-fillings, and in veins associated with quartz. Calcite and gypsum also occur as hydrothermal minerals, and pyrite, together with magnetite and hematite, forms an irregular halo around the mineralized zone. Chlorite-epidote alteration occurs sporadically within Jackass Mountain Group rocks for several kilometres around the deposit.

Since its discovery in 1956, the property has been explored by a variety of surveys, 17,269 metres of diamond drilling and 21,131 metres of percussion drilling, which has identified two zones. The Copper Creek zone has reserves of 280 million tonnes grading 0.261 per cent copper, 0.142 gram per tonne gold, 0.007 per cent molybdenum and 0.514 grams per tonne silver. The Fenton Creek zone is estimated at 18.3 million tonnes grading 0.31 per cent copper and 0.128 grams per tonne gold (George Cross News Letter No. 65 (April 2), 1993 and Imperial Metals Corporation, 1995 Annual Report).

In 1993, Bethlehem Resources Corporation drilled 10 holes totalling 2569 metres. Imperial Metals Corporation held an option on the property in 1995. In 1994 Barrick Gold Inc. acquired Lac Minerals Ltd. and in 2009 drilled 10 holes, totaling 4894 metres.

EMPR AR 1933-186-191; 1946-101; 1956-35; 1959-25; 1960-19;
1961-23; 1966-136; 1967-127
EMPR ASS RPT 278, 411, 968, 4139, 7802, 8874, 10660, *16938, *23243, *31428
EMPR EXPL 1979-194; 1980-282; 1981-239; 1988-C132
EMPR FIELDWORK 1980, pp. 117-119; 1987, pp. 105-123
EMPR GEM 1970-216; 1971-326
EMPR MAP 65 (1989)
EMPR OF 1988-9; 1992-1; 1994-1; 1998-8-F, pp. 1-60; 1998-8-K,
pp. 1-22
EMPR PF (Magnetic survey map, New Jersey Zinc; Geology map, J.M.
Carr, 1961; Field notes)
EMR MIN BULL MR 166; 223 B.C. 186
EMR MP CORPFILE (Copper Giant Mining Corporation Ltd.)
EMR MP RESFILE (Poison Mountain)
GSC MAP 29-1963
GSC OF 534; 2207
GSC SUM RPT 1920, Pt. A, pp. 70-81
CIM Special Volume *15, pp. 323-328; *46, pp. 343-351
GCNL #8, 1974; #186, 1975; #50, 1976; #183, 1979; #53,#228, 1980;
#37, 1981; #65, 1993
N MINER Mar.5, 1981; Mar.1, 1989; Feb.17, 1992
Canadian Financial Journal Sept.5, 1973
Imperial Metals Corporation, 1995 Annual Report
Placer Dome File