The ALCO showing straddles Burrell Creek approximately 4.5 kilometres south of Mount Franklin.
The showing is hosted by an unnamed Middle Jurassic granodiorite intrusion, which is cut by and overlain to the north by andesite dikes and flows of the Eocene Marron Formation, Penticton Group. Limestone of the Devonian-Triassic Harper Ranch Group forms small pendants in the area. Andesite and tuff in this area may also be part of the Harper Ranch Group.
The ALCO consists of fracture controlled chalcopyrite and lessor molybdenite mineralization in a broad, but weakly developed stockwork. Pyrite and thin quartz veinlets, 1 to 2 millimetres wide, are common. Bornite has been noted but is rare. The fractures are spaced 3 to 15 metres apart and generally trend east-southeast and dip to the south. A second, subordinate fracture set strike northeast and dip to the north. Sericitic alteration is well developed in the better mineralized areas. Propylitic (chlorite and epidote) alteration is pervasive but generally weak. Where the stockwork cuts through limestone pendants, small lenses and stringers of pyrite, chalcopyrite and bornite have been found.
The earliest record of work on the ALCO showing is a 1906 Minister of Mines Annual Report which describes 2 shafts, each 3.6 metres deep, and a 30-metre long open cut. The property, known as the COPPER GROUP, was owned by J. Gelinas, D. Morrison and A. Omon. In 1912, the B.C. Copper Company held a lease on the COPPER and RIVERSIDE claims. By 1923, an adit on COPPER NO. 2, located 320 metres east-northeast of one of the shafts, had been driven 27 metres. A 9-metre adit is also reported on the LEAH claim 730 metres south-southwest of the shaft. In 1928, the COPPER NO. 2 adit had been extended to 30 metres. Pyrite, carrying low gold and silver values, is noted. Only one shaft, 24 metres deep is mentioned in reports from the 1920s. In 1932, high-grade gold values are reported from the COPPER NO. 2 adit (Minister of Mines Annual Report 1932, page 122). No assay values are given. The ore consists of pyrite in a quartz gangue, which was found near the contact between the granodiorite and the limestone.
In 1968, the showing was staked as the DOE 1-2 and BEAR 1-8 claims by Boundary Exploration Ltd. A geological mapping program was carried out by Newmont Mining Corporation of Canada Ltd.
In 1975-76, Rio Tinto Canadian Exploration Limited carried out a major program on the ALCO, ALCO 2 and ALCO 3 claims. In 1975, the property was mapped and a small soil sampling program was carried out. In 1976, they carried out a 7-hole, 640-metre percussion drill program, additional mapping and soil sampling, and magnetometer, induced polarization, and radiometric surveys. The geophysical surveys produced complex, although inconclusive, patterns of anomalies. The results of the drilling are unknown.
In 1980, Brenda Mines Ltd. carried out a program of mapping, line cutting and soil geochemical surveys. Copper and molybdenum anomalies were associated with the areas of granodiorite.
In 1981, Brenda Mines Ltd. carried out a 4-hole, 313-metre diamond-drill program. One drillhole (A-81-1) was collared about 60 metres southwest of the shaft. This drillhole intersected a sericitic and propylitically altered granodiorite containing a weakly developed porphyry copper-molybdenum stockwork. The best intersection was 0.268 per cent copper and 0.028 per cent molybdenum over 2 metres; lead, zinc, silver and gold values were very low (Assessment Report 9682). The other drillholes were poorly mineralized.
