The approximate centre of the Cariboo-Amelia underground workings is located at 1333 metres elevation on the southeastern slopes of Baldy Mountain. The occurrence is part of the historic Camp McKinney, located 9 kilometres north-northwest of Bridesville, British Columbia.
The Cariboo-Amelia occurrence was first located on a group of eight Crown-granted claims: Emma (Lot 270), Alice (Lot 271), Cariboo (Lot 272), Amelia (Lot 273), Maple Leaf (Lot 613), Sawtooth (Lot 952), Okanagan (Lot 274) and Wiarton (Lot 856) (082ESW217).
Underground mining began soon after the discovery of the Cariboo vein in 1887. G. McAuley and Associates formed the Cariboo-Mining and Milling Company and erected the first 10-stamp mill in 1894. By 1898, the Cariboo McKinney Mining and Milling Company Limited was formed to take over the operation and milling capacity was increased by 10 stamps. At the end of 1903, mining ceased as exploration failed to find the eastern extension, beyond a north-striking fault. The workings at this time consisted of 110-metre vertical shaft to the No. 4 level and a winze to the No. 6 level.
The Consolidated Mining and Smelting Company optioned 29 claims of the McKinney camp and limited surface exploration was conducted. In 1934, the Bralco Development and Investment Company optioned the Cariboo-Amelia claim group. An effort was made to discover the western extension of the Cariboo vein with 5 diamond-drill holes. Pioneer Gold Mines of B.C. Ltd. optioned the property in 1939. Underground drilling from the Nos. 4 and 5 levels and surface diamond drilling to the north explored the eastern extension. Results were poor and the option dropped. In the following year, G. Boag and Associated mined pillars and stoped remnants above the tunnel level. In 1941, Highland-Bell Ltd. explored the Wiarton claim, mined ore and developed 61 metres of drifts and crosscuts above the tunnel level. The lease reverted by the end of the year, however. From 1942 to 1946, E. Wanke and Associates dewatered the mine to the No. 2 level and resumed mining.
In 1957, the eastern extension of the Cariboo vein was discovered by surface diamond drilling under option to W.E. McArther. R. Hunstone and Associates (H. & W. Mining Co. Ltd.) optioned the property in 1958. After dewatering the main shaft, a crosscut was driven 73 metres into the hangingwall of the vein on the No. 5 level. The faulted portion of the vein was intersected and drifted for 18 metres. Under option to McKinney Gold Mines Ltd., a new shaft was completed to 152 metres depth and new Nos. 5 and 6 levels were developed for 229 metres and 305 metres, respectively. By 1962, the No. 6 level was extended 137 metres east but 792 metres of diamond drilling failed to locate additional ore.
From 1983 to 1986 the property was under option to Zuni Energy Corp., who conducted exploration work consisting of geological and geophysical surveys, trenching and rock sampling. In 1987, Ark Energy Ltd. conducted a 600-metre, surface diamond drilling program near the east-section of the mine but failed to intersect the east extension. Three holes drilled on the Wiarton Crown grant intersected the vein at about 24 metres vertical depth. The mine was dewatered in 1987 and sampling was conducted on the east end of the Nos. 5 and 6 levels. Ark Energy Ltd. optioned the property to Gold Power Resources Ltd. and Lemming Resources Ltd. in 1989. Under option, a surface drill program totalling 872 metres and surface trenching was conducted on the Wiarton Crown grant. Two holes intersected the Cariboo vein 70 and 128 metres east of the 1960 shaft. Current exploration (1997) is being conducted by Gold City Resources, with a 100 per cent interest in 1150 hectares covering Camp McKinney and including the Cariboo-Amelia occurrence.
The Camp McKinney area is underlain by interbanded and intergrading Carboniferous to Permian Anarchist Group metamorphosed sediments and volcanics. The group is mainly sedimentary and consists of greenstone, locally calcareous, altered quartzite and argillaceous quartzite, greywacke, limestone and locally micaceous quartzite and calcareous biotite schist. The minor volcanics are described as mainly altered andesitic and basaltic flows.
Granite and granodiorite of the Middle Jurassic Nelson intrusions have intruded the Anarchist Group to the west and south as small stocks and plugs. Along the contacts of these intrusions the Anarchist rocks have been deformed and hydrothermally altered. Younger dikes of felsic and mafic composition intrude both stratified and granitic rocks and may have been associated with faults related to these granitic intrusions.
The major regional structural feature in the vicinity of the Cariboo-Amelia occurrence is a northeast trending fault zone 5 kilometres to the east. The fault follows Conkle Creek, Conkle Lake and Jolly Creek.
Faulting in the Cariboo-Amelia mine area is postmineral and widespread. Major east dipping, low angle thrust faults in the central portion of the mine have displaced the hanging wall to the northwest by about 122 metres. An east-dipping fault has also moved the hangingwall south by about 91 metres. The complexly faulted and folded rocks are predominantly northwest striking and steeply to moderately northeast dipping.
At the Cariboo-Amelia mine, the main quartz vein, commonly referred to as the Cariboo or McKinney vein, is hosted by a complex interlayered succession of metabasalt flows, tuffs and minor marble of the Anarchist Group. The rocks appear to be metamorphosed to upper greenschist or amphibolite facies. Metabasalts are sheared and altered to sericite, carbonate and quartz along vein walls. Plagioclase, amphibole, biotite, chlorite, carbonate, quartz and pyrrhotite comprise metavolcanics. Marble forms a 9-metre thick band striking northwest through the Amelia claim. Other thin marble bands are found within metasediments. Metasedimentary rocks include successions of interbedded quartzite and argillite. Intense deformation and hydrothermal alteration comprising silicification and carbonatization is evident in the hostrocks. Complexly folded and faulted metasediments and metavolcanics have a regional northwest strike with moderate to steep northeast dips. Surface mapping has outlined a northwest plunging recumbent synform. The limbs dip moderately to steeply to the northeast.
The Cariboo/McKinney vein crosscuts all rock types (except the mafic dikes), commonly at a high angle to bedding. The vein is more regular where it crosscuts competent metabasalts and irregular with offshoots where it crosscuts quartzite and other metasediments. The vein itself is offset by numerous faults having a variety of orientations which include low angle thrust faults with displacements of up to 120 metres.
The Cariboo/McKinney vein strikes 090 degrees and dips vertically with local steep south dips. It has been mined over a strike length of 754 metres, and to a depth of 107 metres in the west section of the No. 4 level and 171 metres in the east sections of the Nos. 5 and 6 levels. The total surface trace of the vein is 1630 metres long on the Crown grants, and an additional 780 metres east and west. The vein width is quite variable over short distances along strike and dip. Widths vary from 0.25 up to 3.5 metres.
The Cariboo/McKinney vein is composed of white quartz and pyrite with lesser sphalerite, galena, chalcopyrite and rare tetrahedrite and pyrrhotite. Visible native gold is locally prominent. Higher gold grades occur where the vein hosts narrow massive sulphide bands(up to 3 to 5 per cent) or higher sphalerite and galena concentrations (Assessment Report 20668). Locally the quartz appears bluish and chalcedonic, and contains free gold (Bulletin 6). The vein has been classified as a mesothermal vein based on its: (1) strike length, (2) the character of the quartz and sulphides and (3) its similarity to mesothermal veins of the nearby Fairview Camp (Assessment Report 20668).
The Cariboo-Amelia occurrence has been the most significant mineral deposit and mineral producer from Camp McKinney. It was British Columbia's first dividend paying lode gold mine (Assessment Report 20668) with an average recovered grade of 24.68 grams per tonne gold (Gold City Mining Corp. (1996): Geological/Mineral Deposit Field Trip Report). Over its intermittent 68 year mine life, from 1894 to 1962, the Cariboo-Amelia produced 124,452 tonnes ore of which 112,254 tonnes is reported milled on-site. Recovery included 2,538,101 grams of gold, 1,008,979 grams of silver, 51,393 kilograms of lead and 89,875 kilograms of zinc, with lead and zinc recovered since 1940. The ore (about 10,243 tonnes) from 1960 to 1962, was also used as a siliceous flux in the Trail smelter.
In 1998, Blackfoot Resources Ltd. optioned the property from Consolidated Gold City Mining Corp. and conducted drilling.