Chalcopyrite with malachite and azuirte
Virtual Museum ID: 19-EKM07
Chalcopyrite is an important copper ore mineral found in many different types of copper deposit. It is sometimes mistaken for Gold because of its bright yellow colour; however, it is harder, more common, and chalcopyrite commonly occurs with other copper sulphide minerals such as bornite and weathers to malachite and azurite.
Malachite is a green hydrous copper carbonate mineral that forms near the Earth's surface as other copper ore minerals, like bornite, are exposed to the atmosphere and weather, or oxidize. Malachite often forms as coatings on joints and fractures or in rock cavities. It often occurs in banded "botryoidal" masses. Botryoidal means is has an appearance similar to a bunch of grapes. Malachite commonly occurs with azurite, another secondary copper mineral that forms by weathering copper sulphides. Together, they are clues that more extensive copper mineralization might be nearby.
Azurite forms by the weathering of other copper minerals. Copper ore minerals like chalcocite and bornite “rust” when they come into contact with oxygen in the air or groundwater. This causes their atomic structure to change to become brightly coloured azurite. Azurite is often found at the surface above buried copper deposits and is a useful clue for prospectors and geologists looking for new deposits.
The information listed below relates to the current holding location or collection that the sample is from, and whether the item is viewable at that location or is part of a private collection. Coordinates are given as guides, and we remind you that collecting specimens from these locations is not allowed. Caution is advised visiting such sites and Below BC assumes no responsibility for any injuries or trespassing charges that may occur as a result of the viewer entering these sites.
Original Collection:East Kootenay Chamber of Mine (EKM)
Virtual Museum ID:19-EKM07
Date Added to VM:2019-06-14
Sample Origin:Bull River, B.C.
Specific Site:Bull-Galloway Mine
Datum:11 (NAD 83)
Primary Features:Chalcopyrite with malachite and azuirte
Primary Mineral Formula:CuFeS 2 · Cu2(CO3)(OH)2 · Cu3(CO3)2(OH)2
Advanced Geological Information
The following section provides geological data relating to the specimen or the site it was collected from, when available. Information has been obtained from various sources including private and government datasets but may not be up to date. Any geological time periods or ages listed often relate to the primary geology of the area, and may not be the actual date of an event such as mineral formation.
Geological Formation:Helikian Aldridge Formation (Purcell Supergroup)
Stratigraphic Age:1433 Million Years
Geological Terrane:Ancestral North America
The property is located 23 kilometres due west of Fernie, extending north from the Bull River, astride Burntbridge Creek, between 900 and 1070 metres elevation.
In the Bull River mine area, quartz-siderite veins and veinlets host irregular blebs of chalcopyrite and disseminated pyrite and pyrrhotite. Malachite and azurite coat fractures in both vein and country rock as secondary minerals. Chalcopyrite is observed as fracture-fillings in less weathered host rocks. The veins are concentrated in highly fractured and sheared zones in dark grey laminated argillites and quartzites of the Helikian Aldridge Formation (Purcell Supergroup). The major veins ranged from 0.3 to 6 metres in width. The sediments are characterized by bands rich in fine, well-crystallized pyrite. The area is also intersected by dykes which are spatially related to mineralization.
A number of claims were located in the vicinity of Burntbridge Creek in about 1896. The Silver Chief, Silver Reef, and Silver Buckeye claims were owned by David Griffith of Wild Horse Creek. Development work was done in a 30-metre crosscut adit and 4.5-metre shaft. The Daisy Fr. claim, owned by Thomas Bevans, was developed by shallow pits and open cuts. The Silver Chief (Lot 3548) and Sirdar (Lot 3554) were Crown-granted to Dave Griffith in 1899.
No further activity was reported until 1927 when the Silver Chief, Sirdar, and Khedive claims were owned by A.B. Fenwick of Bull River. The workings at that time included a crosscut adit about 40 metres in length.
The ground was subsequently restaked but no further activity was reported until 1968.
Mineral Lease M-69 comprising Lots 14717-14752, which included the Big Bonanza 1-4, June 1-6, and Bonanza 1-30 claims, was owned in 1968 by J. Van Koughnett.
Placid Oil Company optioned the property and during 1968 carried out geological mapping, a megnetometer survey, trenching and stripping. A number of old pits and 460 metres of old adit were cleaned out. Diamond drilling was done in 23 surface holes (2260 metres) and 5 underground holes (310 metres). The property was expanded to include 62 located claims. Exploration work during 1969 included soil sampling, induced polarization and electromagnetic surveys, and 5415 metres of surface diamond drilling in 45 holes. This work indicated two orebodies amenable to open pit mining. A 750-tone per day mill was built and milling operations commenced on October 1, 1971. Mining had begun in Pit 2 in August with commencement of overburden removal. Exploratory drilling totalling 1168 metres was done in the vicinity of the tailings pond. Preproduction stripping of No. 1 pit began in 1972. Mining in No. 2 pit was completed in April 1973 and operations transferred to No. 1 pit. After completion of No. 2 pit, the pit was backfilled with material from No. 1 pit and almost completely refilled. Mining ceased in March 1974 because of depletion of open pit ore reserves. Milling of stockpiled ore continued until June 10th, 1974, when operations ceased.
In order to determine the feasibility of mining the underground reserves the company elected to sink a 200-metre exploration decline to intersect zone A, however, after several abortive attempts to collar the portal, the program was abandoned due to very blocky ground which could not be economically stabilized. Reserves are reported as 90,720 tonnes at 1.3 per cent copper, 0.31 gram per tonne gold, 21.77 grams per tonne silver (EMPR Reserves Map, 1984). Although milling operations began in October 1971 there is no available record of production for that year. During the period 1971-1974 inclusive, 471,900 tonnes of ore were milled. From this ore 126,123 grams of gold, 6,353,628 grams of silver, and 7,256,050 kilograms of copper were recovered.
Inferred (proven/probable/possible) reserves at Bull River are 2 million tonnes of copper-silver-gold ore (grade not given) (Open File 1992-1).
In 1996, R.H. Stanfield and Associates (Bul River Mineral Corp.) commenced excavation of a 1500-metre decline to provide access for underground drilling and sampling. Stanfield acquired the property from Placid Oil Co., who report reserves of 664,500 tonnes averaging 1.95 per cent copper, at a 1.00 per cent copper cut-off and minimum thickness of 1.2 metres (Assessment Report 23786). Stanfield has drilled the property since 1982.
In 1998, Bul River Mineral Corporation's exploration activity included 1100 metres on the 16 per cent decline (total 2000 metres), 725 metres level advance, 195 metres raise bore, 6508 metres of underground BQTK diamond drilling, 1144 metres of surface diamond drilling and 367 metres of percussion drilling. Measured and indicated resources are reported as 5.3 million tonnes, averaging 2.25 per cent copper, 36.34 grams per tonne silver and 12.0 grams per tonne gold (Bul River Mineral Corporation, 1998; Exploration in BC 1998, page 69). Calculation details are unavailable.
By December 1999 the decline had advanced approximately 3800 metres to the 900-foot level from surface. The company reported they spent $11.5 million in 1999 on underground development, bulk sampling and analytical work. This included extending the decline by 554 metres, 1424 metres of level development, 11,169 metres of underground drilling, 1741 metres of surface drilling and a 306-metre raise. Ministry geologists visited the site in June 1999 and took ten splits of mineralized vein material from three diamond-drill holes and five rock chip samples from veins exposed in the underground workings at the 300 and 500 levels for independent assay. The median gold grade returned by fire assay from ten mineralized core samples was 0.28 gram per tonne with the best intersect being 4.77 grams per tonne over 1.1 metres. Neutron activation results were in close agreement with those by fire assay.
In 2000, an exploratory underground drill hole (BRUOO-60) within the Gallowai-Bull River Mine (Mining Lease-93) workings to ascertain possible economic mineralization to the west of the current underground operation. Nine samples were collected from a 5.3 metre section of carbonate- rich vein containing pyrrhotite, pyrite and elevated copper values (Assessment Report 26638).