Bornite and chalcopyrite
Virtual Museum ID: 19-RM01
Bornite is an important copper ore mineral found in many different types of copper deposit. It is also known as peacock ore because of its iridescent purple-blue-green tarnish. Fresh bornite, however, is copper red. Bornite commonly occurs with other copper sulphide minerals such as chalcocite and weathers, or “oxidizes”, to malachite.
Chalcopyrite is the most common ore mineral for copper and is a sulphide of iron and copper. Chalco comes from the Greek word chalko, meaning copper. Chalcopyrite is commonly found in sulphide deposits in most ore-forming environments. Chalcopyrite is an important copper ore mineral found in many different types of copper deposit. A characteristic deep brass yellow colour and iridescent green-to-purple weathering surfaces distinguish chalcopyrite from gold and sulphides such as pyrite. 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.
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:Rossland Museum & Discovery Centre (RM)
Virtual Museum ID:19-RM01
Date Added to VM:2019-06-08
Sample Origin:Rossland, B.C.
Specific Site:Velvet Mine
Datum:11 (NAD 83)
Primary Features:Bornite and chalcopyrite
Primary Mineral Formula:Cu5FeS4 · CuFeS2
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:Rossland Group Volcanics
Stratigraphic Age:541 to 251.902 million years ago
Geological Terrane:Quesnel, Plutonic Rocks
The Velvet occurrence is underlain by Paleozoic serpentinite which forms a huge roof pendant surrounded by syenite of the Middle Eocene Coryell Intrusions. Within the serpentinite are large xenoliths of Rossland Group volcanic rocks, particularly on the Portland claim. The rocks within the pendant are cut by dykes up to 6.0 metres wide, commonly of porphyritic syenite and of medium- grained granodiorite. These dykes are related to the Coryell and Middle to Late Jurassic Nelson intrusions respectively, and in general are parallel with the main shears.
The origin of the copper, gold, silver veins at the Velvet Mine is not well understood. They may be mesothermal structures related to middle Jurassic thrust faults marginal to ophiolitic lithologies; it may be a skarn; it may be that the veins are related to the Middle Eocene Coryell Intrusions (EMPR Bulletin 109, page 48).
The mineralization occurs in replacement veins that strike north and dip steeply to the west. Besides the main or Velvet vein, four other veins are known to exist in its footwall some 18, 40, 58 and 98 metres to the east, respectively. A few small, relatively short east-west striking veins cut the main vein. Ore shoots occur at intersections of the main vein with crosscutting dykes or faults. Mineralization includes specularite, pyrite, chalcopyrite and malachite in a gangue of quartz and calcite. Molybdenite also occurs locally in a gangue of quartz and altered wallrock. Chalcopyrite mineralization is described as typically massive where it occurs along the walls of the ore shoots. Small amounts of scheelite have been seen in the dump and underground workings. As well, lead and zinc were recovered from minor occurrences of galena and sphalerite.
From 1901 to 1964, 88,833 tonnes of ore produced 620,785 grams gold, 664,359 grams silver, 1,154,104 kilograms copper, 37 kilograms lead, and 25 kilograms zinc. In 1982, it was reported that 907 tonnes of ore grading 5.4 grams per tonne gold with other commodities was shipped to the HB mill (082FSW004) of David Minerals Ltd.
The Velvet and Portland Crown-granted claims and several others held by record lie on the northwest slope of Mount Sophia at about 1097 metres elevation. The mine is about 13 kilometres directly southwest of Rossland and 2 kilometres north of the International Boundary.
In April 1896 J. Cromie located the Portland claim and in September of the same year O. Geldness located the Velvet. The two claims were developed separately until 1904. The Velvet claim was acquired in 1897 by Velvet Mines Ltd. and they carried on development work until Velvet-Portland Mines Ltd. was formed in 1904 to acquire both properties. The mine was operated intermittently by the company or by leasers until it was closed in 1916. Granby Consolidated Mining, Smelting & Producing Co. examined the workings in 1918 and subsequently relinquished their option.
Rossland-Velvet Mines Ltd. took over the property in 1920 and intermittent work was carried on by the company or by leasers until 1928 when the mine closed. Velvet Gold Mining Co. Ltd., formed in the fall of 1932 reopened the mine and operated it intermittently until the fall of 1937.
Velgo Mining Incorporated took over the property in 1938 and later in the year leased it to R. Bielli & Associates who subsequently formed the Velvet Leasing Syndicate; the syndicate name was changed in 1941 to Velvet Gold Leasers. The leasers operated until 1942 when the mine was closed. The mine remained closed until 1952 except for a brief period in 1946 when Velvet Gold-Copper Mines Incorporated acquired the property and leased it to J. Coryell, Jr. A diamond drilling program was carried out at this time consisting of 7 holes totalling 438 metres from No. 8 level and 4 holes totalling 172 metres from the surface.
In 1952 the property was acquired by Messrs. Kenward and Sweet. Leasers began mining operations and in 1953 built a small mill. Mid-West Copper & Uranium Mines Ltd. acquired the property in 1955 and intermittent operations were carried on by the company or by leasers. A new mill was built and put into operation in 1956. In October 1964 the company was reorganized under the name Mid-West Mines Ltd. The property is developed by a vertical shaft serving 6 levels, of which No. 4 and No. 6 are accessible from the surface by adits. A 527-metre long adit on No. 8 level is connected to No. 6 level by a raise. Around 1978, Velvet Exploration Co. Ltd. (formerly Kendal Mining and Exploration Company Limited) acquired the mine. In 1980, they carried out 914.4 metres of drilling of which 244 metres was diamond drilling, the rest was percussion. In August 1982 it was reported that 1,000 tons grading 5.48 grams per tonne gold and other commodities were shipped to the H.B. mill of David Minerals Ltd. in Salmo.