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File Created: 24-Jul-85 by BC Geological Survey (BCGS)
Last Edit:  18-Feb-91 by Laura L. Coughlan(LLC)

Summary Help Help

Name MOTHERLODE (L.8818), INDEPENDENCE (L.8817) Mining Division Nelson
BCGS Map 082F015
Status Past Producer NTS Map 082F03E
Latitude 49º 09' 51" N UTM 11 (NAD 83)
Longitude 117º 07' 00" W Northing 5445712
Easting 491495
Commodities Gold, Silver, Lead, Zinc, Copper Deposit Types I01 : Au-quartz veins
Tectonic Belt Omineca Terrane Ancestral North America
Capsule Geology

The Sheep Creek Mining Camp consists of auriferous sulphide mineralization within a regional system of quartz veins controlled by faults. The camp hosts four distinct fault/fracture systems. All productive veins are associated with faults trending northeast and dipping southeast. The veins are particularly productive where they cross the axis of the two regional, northerly trending anticlines which dominate the geology of the camp. In addition there are a few northwest trending strike slip faults, north trending normal faults and flat faults, on which the hanging wall has been thrust westwards.

Ore occurs in shoots and is almost without exception confined to parts of fault zones in which one or both walls are quartzite. Other parts of the veins are either too narrow or low grade to be economic. The ore shoots are found at the intersection of northeast faults with quartzite stratigraphy, particularly the Upper Nugget and Upper Navada Members of the Quartzite Range Formation (correlative with rocks of the Lower Cambrian Hamill Group). The underlying Motherlode quartzite is, without obvious reason, almost completely barren of economic gold mineralization. The veins contain a quartz gangue containing pyrite with lesser amounts of pyrrhotite, chalcopyrite, galena, and sphalerite. Visible gold is rare. Precious metal grades are exceedingly variable and zones of high grade appear to be distributed randomly. Such zones or ore shoots are rarely greater than a few tens of metres in size.

Throughout the camp economic mineralization is found within a vertical range of less than 500 metres in any given vein and from north to south in the camp this vertical range occurs at progressively lower elevations. At the north end of the camp near Reno Mountain the economic zone lies at about 1675 to 2150 metres elevation and at the south end near Mount Waldie the zone is entirely below 915 metres above sea level. Above the economic zone the veins may occur but are generally too narrow and below the zone the veins usually persist but are commonly wider and of lower grade. Higher grades of greater than 150 grams per tonne are generally restricted to the top of the zone.

The Motherlode occurrence is south of the Nugget (082FSW040) and occurs within coarse, white to grey quartzite with interbeds of argillite and schist of the Lower Cambrian Quartzite Range Formation. The most westerly workings are close to the contact with the lower part of the Lower Cambrian Reno Formation (correlative with rocks of the Hamill Group). Two gold bearing ore shoots, the Motherlode and Independence, were discovered on surface within the Moderlode vein which strikes 70 to 75 degrees and dips near vertically. The ore shoots rarely exceed 1 metre. They are about 100 metres along strike and the Independence ore shoot has been tested to a depth of about 190 metres. The Motherlode ore shoot was tested to a depth of about 147 metres. The two shoots are 168 metres apart and there is one very small ore shoot between them.

Mineralization consists of a gangue of vein quartz with some crushed country rock which has been oxidized leaving brown iron oxides and free gold. Oxidation is documented at the lowest mining levels.

Production figures have been intertwined historically between the Motherlode and Nugget (082FSW040) and later the Reno (082FSW036) occurrence. These production values have been separated out among the three as best as possible but some error may still exist.

Production from these shoots between 1906 and 1985 amounted to about 67,444 tonnes which contained 1,257 kilograms of gold and 588 kilograms of silver, 3010 kilograms of copper, 11,000 kilograms of lead and 4260 kilograms of zinc. Of the total mined, about 64,760 tonnes was mined between 1906 and 1922. Indicated reserves are reported to total 3,152 tonnes grading 12.0 grams per tonne gold (George Cross News Letter No.217 (November 12), 1987).

EMPR AR 1906-148,248; 1907-103,213; 1908-110,246; 1909-119,276;  1910-109,243; 1911-157,160; 1912-155,322; 1913-130,419; 1914-  510; 1916-205; 1918-173; 1919-159; 1920-131; 1922-205; 1924-191;  1932-190; 1933-229; 1935-E30; 1936-E47; 1938-A36,E39; 1939-39,83;  1940-26,68; 1941-26,67; 1942-64
EMPR BULL 1; *31, pp. 41,51,62,70,74,80; 41; 109
EMPR FIELDWORK 1987, pp. 19-30; 1988, pp. 33-43; 1989, pp. 11-27;  1990, pp. 9-31
EMPR GEM 1974-24
EMPR OF 1988-1; 1989-11; 1990-8; 1990-9; 1991-2
EMPR PF (Starr, C.C. (1925): Report of Examination of the Nugget and  Motherlode Mines; Starr, C.C. (1940): Geological Notes and  Impressions on the Motherlode, Nugget and Bluestone Veins;  Nugget-Motherlode Mine (underground workings, 1"=100'), 1923;  Endersby, S.A. (1974): Letter to J.E. McMynn, 2 p.)
GSC MAP 50-19A; 299A; 1068; 1090A; 1091A; *1145A; 1956-3
GSC MEM *172, p. 30; 308, p. 174
GSC OF 1195
GCNL #4, 1978; #217, 1987
V STOCKWATCH Nov. 10, 1987