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File Created: 24-Jul-85 by BC Geological Survey (BCGS)
Last Edit:  23-Oct-14 by George Owsiacki(GO)

Summary Help Help

NMI 104P5 Asb1
BCGS Map 104P031
Status Past Producer NTS Map 104P05W
Latitude 59º 19' 30" N UTM 09 (NAD 83)
Longitude 129º 49' 05" W Northing 6576528
Easting 453445
Commodities Asbestos, Chrysotile, Jade/Nephrite, Gemstones, Magnesium Deposit Types M06 : Ultramafic-hosted asbestos
Q01 : Jade
T01 : Tailings
Tectonic Belt Omineca Terrane Slide Mountain
Capsule Geology

The Cassiar asbestos mine is located about 4.5 kilometres north-northeast of the Cassiar townsite.

The area is underlain by four major thrust sheets, distinguished on McDame Mountain, of the Devonian to Triassic Sylvester Allochthon. These comprise greenstones, argillites, limestones, ultramafites and ultramafic bodies of variable size, shape and form. These bodies of antigorite serpentinized harzburgites occur along at least three distinct horizons which are probably major thrust fault surfaces. The lowest horizon occurs just above the Sylvester basal thrust fault, and contains a serpentinite thrust slice that hosts the Cassiar and McDame (104P 084) deposits. There were two episodes of faulting postulated with asbestos forming during the change from normal to dextral motion on a north-trending fault that transects the serpentinite ("45 degree shear").

The Cassiar pit occupies a zone of anomalous structure, with a north trending, high-angle fault (Marble Creek fault) juxtaposing bedded chert (Sylvester) to the east and graptolitic Ordovician-Silurian Road River Group slate to the west. The latter is complexly imbricated with slivers of dolostone (Lower Devonian Tapioca sandstone or Middle-Upper Devonian McDame Group) below the Sylvester basal thrust.

The Cassiar orebody is roughly crescent-shaped with northeast and southeast trending horns. The orebody as a whole dips about 45 degrees east and measures approximately 600 by 150 by 150 metres. North striking, east dipping thrusts and shears slice the orebody into a number of massive blocks with well-developed systems of conjugate joints, most of which contain long cross-fibre chrysotile. The orientation of joint systems within successive blocks varies widely, but tends to favour two directions, north-northwest to north-northeast, and east-southeast.

The orebody is a fibre-bearing zone containing upwards of 10 per cent cross-fibre chrysotile asbestos varying in length up to 3 centimetres. Most veins are the two-fibre type, with a central parting. The short fibre component is also significant economically. There are two generations of asbestos veins with different orientations. Magnetite is abundant in partings and along vein walls. Pyrite and jade also occur within the serpentinite.

Post-vein shearing is most apparent in the footwall of the deposit. In country rocks near the orebody, there are many steeply dipping veins with quartz, tremolite, talc, zoisite and carbonates.

Reserves at the Cassiar Asbestos mine were exhausted in June 1989, after 38 years of production. Stockpiled ore (1.4 million tonnes) from the pit supplied sufficient millfeed while the McDame deposit was being prepared for production. The McDame deposit commenced production in February, 1991. Large, unknown quantities of jade were also produced over the years.

Reserves at the Cassiar mine are approximately 17 million tonnes grading 4.2 per cent asbestos and 23.5 per cent magnesium in a low-grade stockpile (waste from the former dry-milling operation) determined by drilling on 30 metre centres in the mid-1980s (P. Wojdak, personal communication, 1994 and Exploration and Mining in British Columbia 1998, page 25).

Jedway Enterprises recovered 50 tonnes of jade from the old Cassiar Asbestos dumps in 1998. Cassiar Mining Inc., a wholly owned subsidiary of Minroc Mines Inc., expected to produce at a rate of 1000 tonnes of asbestos fibre per month from August to October 1998. A total of 20,000 tonnes was shipped. Minroc is conducting a feasibility study to assess magnesium recovery in the tailings. Minroc changed its name to Cassiar Mines & Metals Inc. in June 1999.

In July 1999, Aluminum of Korea Ltd. (KORALU) entered into an agreement with Cassiar to acquire 35 per cent of the Magnesium Metal Project. The serpentine stockpile of 20 million tonnes contains 3630 million kilograms of magnesium metal and 700 million kilograms of chrysotile fibre (Cassiar Mines & Metals Inc., Press Release, December 27, 1999). In April 2000, Cassiar changed its name to Cassiar Magnesium Inc. In 2000, Cassiar Magnesium Inc. dry milled surface stockpiles of chrysolite, with approximately 6 million tonnes of 7 per cent fibre outlined, to produce 60 to 70 tonnes per day of long and intermediate fibre. The dry mill facility was damaged by fire in December 2000 and production has been suspended.

EMPR AR 1950-207-214; *1951-212-214; 1952-243; 1953-181; 1954-174,175; *1955-88-90; 1956-146-148; 1957-76,77; 1958-83; 1959-150,151; 1960-127,128; 1961-138; 1962-143; 1963-137; 1964-179; 1965-256; 1966-259; 1967-299; 1968-295
EMPR ASS RPT *9525, *10655
EMPR ENG INSP (Mine plans); Annual Report 1989, 1990
EMPR EXPL 1981-323; 1986-A41,A48; 1987-A42; 1989-229-236; 1996-A14,A24; 1998-13,25
EMPR FIELDWORK 1978, pp. 51-60; 1979, pp. 80-88; 1987, pp. 245-248; 1988, pp. 323-337; 1989, pp. 223-228
EMPR GEM 1969-379; 1970-487; 1971-451; 1972-573-577; 1973-536,537; 1974-370,371
EMPR INF CIRC 1985-1, p. 17; 1986-1, p. 26; 1989-1, p. 18; 1990-1, p. 25; 1991-1, p. 40; 1996-1, p. 10; 1997-1, pp. 13,23; 1998-1, p. 15; 1999-1, pp. 12,14; 2000-1, pp. 9,18
EMPR MINING 1975-1980, p. 41; 1981-1985, p. 52; 1986-1987, p. 78; 1988, p. 78; Jan./Feb. 1991, Vol.2, No.1, pp. 8-11
EMPR MER 1984, p. 17; 1985, p. 26
EMPR MP MAP 1992-13
EMPR OF 1988-19; 1989-9; 1992-1; 1992-3; 1992-9; 1995-25; 1996-11
EMPR PF (*Plumb, W.N. (1968): The Geology of the Cassiar Asbestos Deposit; O'Grady, B.T. (1950): Preliminary Report on Asbestos occurrences, Northwest of McDame Lake, Stikine; Asbestos, 1972, Cassiar Mining Corp., date unknown; Cassiar Asbestos Mine, Prospectus; Cassiar Mining Corp. Annual Report, 1987; "Shifting Fortunes" article in BC Business Magazine Feb. 1989; Cassiar Mining Corporation, Annual Reports (excerpts), 1986, 1987, 1988, 1989, 1990); Jakubec, J. (1992): Support at Cassiar Underground Mine, MASSMIN 92; Minroc Mines Inc. Website (Aug. 1999): Cassiar Redevelopment 2000, 14 pp.)
EMR MP CORPFILE (Canwest Exploration Company Ltd., Cassiar Resources
GSC EC GEOL 1963, pp. 123-126
GSC MAP 381A; 1110A
GSC MEM 194; *319, pp. 123-126
GSC P 78-19, pp. 32,35
GSC OF 2779
CIM Vol.71, No.792, April 1978; Vol.79, No.896, 1986
GCNL #66,#163,#191,#214, Oct.4, Nov.7, 1978; #163, 1979; #65, 1976; #69, Apr.29, 1977; #63, 1979; #61,#96, 1980; #41,#85,#228,#231, 1982; #19,#146, 1984; #26,#78,#230,#247, 1985; #125, 1986; #78,#143, 1985; #37, 1986; #105, 1987; *#45(Mar.5), 1990; #14(Jan.21), #26(Feb.6), #53(Mar.15), 1991; #87(May 5), #90(May 8), #169(Sept.1), 1992
N MINER Jul.19, 1951; Jul.10,31, Oct.30, 1952; Jan.1, Mar.19, Aug.13, Sept.17, 1953; Jan.1,28, Jun.10,17, Oct.14, Dec.16, 1954; Jan.20,13, May 5, Oct.20, Dec.29, 1955; Apr.8, 1976; Apr.21, Aug.11, 1977; Aug.23, 1979; May 4, 1978; Nov.13, 1980; Mar.4, Apr.15, May 6 ,Aug.5, Nov.4, Dec.9, 1982; May 26, Dec.1, 1983; Feb.2, May 17,24, Aug.2, Sept.13, 1984; Apr.25, May 23, Aug.29, Dec.2, 1985; May 18, June16, July7, 1986; Mar., Apr., 1988; Jan.2, Aug.7, Sept.11, 1989; Jan.15, 1990; Mar.30, June 20, 1992; July 19, 1993; June 9, 1997; June 1, Oct.19, 1998; June 14, 1999; Feb.28, Oct.16, 2000
PR REL Mineral Resources Corporation, May 12, 1998; Minroc Mines Inc., Sept.4, 1998; June 4, 1999; Cassiar Mines & Metals Inc. June 8, July 7, Dec.22, 1999; Cassiar Magnesium Inc., April 18, 2000
W MINER Stephens, F.H. Asbestos Corp., August 1964; The Original Cassiar Asbestos Mine, May 1970; Cassiar improves asbestos operations in B.C., November 1981; May 1977; June, Apr., 1979; Aug., Vol.37, pp. 48-54, 1964; Nov., 1981; Apr., 1982
*Burgoyne, A.A. (1985): Geology and Exploration of the McDame asbestos deposit, Cassiar, British Columbia; Paper presented to 87th Annual General Meeting, CIM Apr.22, 1985
*Gabrielse, H. (1960): The Genesis of chrysotile asbestos in the Cassiar asbestos deposit, Northern British Columbia, ECON GEOL Vol.55, No.2, pp. 327-337
Harms, T.A. (1986): Structural and Tectonic Analysis of the Sylvester Allochthon, Northern British Columbia, Implications for Paleogeography and Accretion, Ph.D. Thesis, University of Arizona
*Hewett, F.G. (1984): Cassiar asbestos mine, Cassiar, British Columbia; in the Geology of Industrial Minerals in Canada, CIM Spec. Vol. 29, pp. 258-262
O'Hanley, D.S. (1987): The Origin of Alpine-Peridotite Hosted Chrysotile-Asbestos Deposits (In preparation)
Precambrian Magazine *Vol.34, No.6, pp. 23-30 (June 1961)
Smitheringale, W.V. (1957): The Geology of Canadian Industrial Mineral Deposits, 6th Commonwealth Mining and Metallurgical Congress, 1957, pp. 49-53