Massive pyrite-chalcopyrite ore
Virtual Museum ID: 19-T1-06
bedding defined by occassional thin silica bands
Pyrite is a common iron sulphide mineral found in many different geological settings. It has a brassy-yellow metallic colour that has caused many people to mistake it for gold, giving it the name “Fool’s gold”. Pyrite and gold can be quite easily distinguished from one another: pyrite is less yellow and much lighter and harder than gold, which can be scratched with a pocket knife. Pyrite often forms perfect cubes, which can grow to quite large sizes, because of its crystal structure. The word pyrite comes from the Greek word ‘pyr’ meaning fire, because it will spark if hit with other metal or stone objects.
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:Smithers Exploration Group (SEG)
Virtual Museum ID:19-T1-06
Date Added to VM:2019-08-20
Sample Origin:Campbell River, British Columbia
Specific Site:HW deposit, Myra Falls
Datum:10 (NAD 83)
VM Category:Ore Sample
Primary Features:Massive pyrite-chalcopyrite ore
Primary Mineral Formula:
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:Sicker Group
Stratigraphic Age:358.9 to 419.2 Million Years
Geological Terrane:Wrangell, Plutonic Rocks
Minfile ID:092F 330
The Myra Falls Operation includes the Lynx (092F 071), Myra (092F 072), Price (092F 073) and H-W (092F 330) deposits and associated zones. The H-W volcanogenic massive sulphide deposit occurs within the southern part of the Buttle Lake uplift. This discreet belt of Upper Paleozoic rocks is bounded on the east by Upper Triassic Karmutsen Formation volcanics (Vancouver Group) and on the west by the Early to Middle Jurassic Island Plutonic Suite. The geology of the uplift has recently undergone reinterpretation and the stratigraphy has been reassigned to several new formations of a redefined Sicker Group and the new Buttle Lake Group (formerly the upper part of the Sicker Group), (Juras, 1987; Massey, Personal Communication, 1990).
The new Buttle Lake Group consists of: (1) the Lower Permian(?) Henshaw Formation composed of conglomerate, epiclastic deposits and vitric tuffs; and (2) the Lower Permian to Pennsylvanian Azure Lake Formation (formerly Buttle Lake Formation) consisting of crinoidal limestone and minor chert.
The Sicker Group consists of: (1) the Mississippian or Pennsylvanian(?) Flower Ridge Formation largely comprising coarse mafic pyroclastic deposits; (2) the Lower Mississippian(?) Thelwood Formation, a bedded sequence of siliceous tuffaceous sediments, subaqueous pyroclastic deposits and mafic sills; (3) the Upper Devonian Myra Formation consisting of basaltic to rhyolitic flows and volcaniclastic rocks, lesser epiclastic sediments, argillites and cherts, and massive sulphide mineralization; and (4) the Upper Devonian or older Price Formation comprising feldspar-pyroxene porphyritic andesite flows, flow breccias and minor pyroclastic deposits.
The Price Formation correlates roughly with the Nitinat Formation (Sicker Group) in the Cowichan uplift area. The Myra Formation lies at the boundary of the Fourth Lake (formerly Cameron River Formation) and Nitinat formations (Buttle Lake and Sicker groups respectively), and may thus represent the McLaughlin Ridge Formation in the Cowichan uplift (Juras, 1987, page 15). The Flower Ridge and Thelwood formations correlate chronologically but not lithologically with the Fourth Lake Formation, and the Azure Lake Formation correlates with the Mount Mark Formation (Buttle Lake Group).
The Buttle Lake uplift stratigraphy indicates deposition in a rift basin in an island arc environment. It has been intruded by granitic dykes related mainly to the Island Plutonic Suite. A 1- kilometre wide stock of Tertiary intrusives lies about 1 kilometre to the north. This stock (formerly called Catface Intrusions) probably has closest affinity to the new Mount Washington Intrusive Suite of Late Eocene to Early Oligocene age (Nick Massey, Personal Communication, May 1990).
The major occurrences in the uplift lie along a northwest striking, 65 degree southwest to steeply northeast dipping zone that is approximately 6 kilometres long. The rocks have been metamorphosed to lower greenschist facies, and have been deformed along northwest trending subhorizontal open folds. Several west- northwest to north trending faults, with a maximum lateral displacement of 850 metres, are of regional importance. The faults are considered to be post-Mesozoic, and are possibly related to Late Cretaceous uplift. The contact between the Myra Formation and the overlying Thelwood formation is marked by a 2.0 to 40.0 metre wide zone of strong schistosity that may represent an Upper Paleozoic low angle fault.
The Myra Formation, dated at 370 million years (Juras, 1987, page 109) contains all of the massive sulphide horizons of the camp. The Lynx (092F 071), Myra (092F 072) and Price (092F 073) deposits lie at the same stratigraphic level (the "Mine Sequence" of Juras). The H-W horizon lies below them, at the base of the Myra Formation, forming a 200 metre thick unit of dacitic to rhyolitic flows and domes, pyroclastic deposits, argillite and massive sulphide mineralization. Westmin Resources' Myra Falls Operations has developed these deposits as four mines. In 1990, the Lynx and H-W mines fed a 4000-tonne per day mill, the Myra mine is depleted and the Price deposit has yet to go into production.
Rocks in the feeder zone below the massive sulphide horizon have undergone sericitization and silicification. Pyrite alteration is evident from disseminated pyrite and pyrite stringer zones.
The lenses of massive sulphides comprise banded chalcopyrite, galena, sphalerite, pyrite and barite, with minor tennantite, bornite and pyrrhotite, and contain gold, silver, and cadmium. The lenses are up to 30 metres thick and pinch out along strike; average thickness is about 18 metres. Pyrite content is much higher than at the other deposits in the area, and averages 70 per cent in the ore grade portion of the mine.
Mineralization in the massive sulphide zone is strongly zoned laterally, with a massive pyrite core containing high copper-zinc to zinc ratios and barite-rich margins with low copper-zinc ratios. The marginal phase contains higher silver and lead than the core zone.
A significant new discovery of massive sulphides (Gap Lens) located underground between the H-W and Lynx mines is believed to be in upper H-W mine stratigraphy. The zone exhibits good stratabound volcanogenic massive sulphide-style and is structurally complicated. Ore mineralogy is very complex (i.e. sphalerite, galena, barite (locally greater than 30 per cent), pyrite, tennantite, chalcocite, bornite and visible electrum). The Gap Lens is 200 by 30 by 60 metres in dimension and is correlative to the HW North Lens trend. Some of the massive sulphide mineralization is caught up in fault slices. The Gap Lens lies stratigraphically above the Battle Lens and is suspected to be a distal facies of the Battle Lens. The Gap Lens is to be reached from the 18-level and mined from existing H-W workings. Drill indicated reserves (4th quarter of 1992) for the Gap Lens are 1.15 million tonnes grading 2.9 grams per tonne gold, 175.5 grams per tonne silver, 2.1 per cent copper, 1.2 per cent lead and 13.9 per cent zinc (Memorandum from T. Schroeter (Senior Geologist, Vancouver), February 10, 1993 - MEG notes "Geology and Exploration of the Battle-Gap Massive Sulphide Lenses", speaker Georgina Price).
Diamond drilling approximately 200 metres southeast of the Gap Lens intersected high-grade material. The discoveries are thought to be separate from Gap Lens ore and are probably part of new, flat-lying, H-W style lenses. This lens has been named the Battle (George Cross News Letter No. 243, 1991).
The Battle Lens is correlative to the H-W Main Lens trend. The Battle Lens is cutoff at the south end by a fault. There is a 330 metre right-lateral offset of the Battle-Gap lenses from the HW orebody (along the Schaft fault). The dimensions of the Battle Lens are 750 by 30 by 250 metres (dip) with drill indicated reserves (4th quarter of 1992) of 3.7 million tonnes grading 1.2 grams per tonne gold, 24.5 grams per tonne silver, 2.7 per cent copper, 0.5 per cent lead and 12.9 per cent zinc (Memorandum from T. Schroeter (Senior Geologist, Vancouver), February 10, 1993 - MEG notes "Geology and Exploration of the Battle-Gap Massive Sulphide Lenses", speaker Georgina Price).
The H-W deposit was brought into production in 1985 and to the end of 1988 and according to Westmin Resources, has contributed 34.8 per cent, or 3,191,370 tonnes, of a total of 9,170,609 tonnes milled at Westmin's Myra Falls Operations. The overall grade of the total ore milled is 2.16 grams per tonne gold, 81.0 grams per tonne silver, 1.83 per cent copper, 0.78 per cent lead and 6.58 per cent zinc. In 1988, the H-W mine contributed 90.5 per cent, or 1,135,887 tonnes, of a total 1,255,124 tonnes of ore sent to the mill that year. The remaining 9.5 per cent came from the Lynx mine (Westmin Resources Limited Annual Report for 1988, page 8).
Production statistics of the H-W mine have been combined with those of the Lynx and Myra mines. Since start-up at the Myra Falls Operations to the end of 1988, the combined milled production totalled 9,162,835 tonnes containing 15,205,759 grams of gold, 615,419,293 grams of silver, 153,750 tonnes of copper, 56,670 tonnes of lead, 525,606 tonnes of zinc and 1,348 tonnes of cadmium.
Proven and probable geological reserves at the Myra Falls operations as of January 1, 1993 are:
Compiled from George Cross News Letter No. 30 (February 12), 1993.
Reserves at January 1, 1994 were estimated by the company at 12.5 million tonnes grading 1.9 per cent copper, 0.5 per cent lead, 6.3 per cent zinc, 45.6 grams per tonne silver and 2.1 grams per tonne gold. Proven, probable and mineable reserves in the Battle zone are 2.5 million tonnes grading 2.0 per cent lead, 10.6 per cent zinc, 1.0 gram per tonne gold and 20.3 grams per tonne silver (Northern Miner - May 22, 1995). The nearby Gap zone contains additional proven and probable reserves of 714,000 tonnes grading 1.5 per cent copper, 0.9 per cent lead, 10.6 per cent zinc, 2.5 grams per tonne gold and 121.2 grams per tonne silver (Information Circular 1995-1, page 6).
During 1994, the Myra Falls mine re-opened in September after a 16-month mining hiatus due to a labour dispute. Reserves estimated by the company at January 1, 1995 were 9,717,800 tonnes grading 1.7 per cent copper, 6.6 per cent zinc, 1.6 grams per tonne gold and 35.6 grams per tonne silver. Reserves in the Battle zone, which is currently being developed and mined, are 2.5 million tonnes grading 2 per cent copper, 10.6 per cent zinc, 1.0 gram per tonne gold and 20.3 grams per tonne silver. There are two other high grade zinc zones closely associated with the Battle - the Gopher and Gnu, which together total about 700,000 tonnes. The Gopher zone is the source of development ore which has been going to the mill since April 1995 (Information Circular 1996-1, page 6).
The Trumpeter zone (H-W horizon) was discovered in early 1992, through surface drilling in Thelwood valley. The drill program leading to discovery was conceived as a test of the postulated fault offset position of 42 and 43 Blocks, across the Myra-Price fault. Drilling in Thelwood valley had been suspended for some 10 years and it took an extensive public information and government approval process to re-establish the program. This program encompassed a number of initiatives to ensure protection of the environment.
The Trumpeter zone, a copper-rich pyritic massive sulphide lens, is believed to be the faulted-off continuation of H-W 42 Block. The zone lies at the same elevation as the H-W mine workings, but approximately 1500 metres towards the southeast.
Drilling in 1994 and early 1995 on the Trumpeter zone successfully tested the mine west strike extension of the zone. Three stratigraphically distinct mineralized intervals were found within the H-W horizon in this area (Upper zone, 43 Block and Trumpeter Upper/Lower). The Upper zone mineralization consists of one to five metre wide intervals along the hangingwall of the H-W horizon and contains 3-15 per cent stringer and disseminated sphalerite and pyrite in rhyolite lapilli tuff deposits. Mineralization in 43 Block is a transported ore type consisting of up to 30 per cent massive sulphide clasts (pyrite, sphalerite, chalcopyrite) in a coarse rhyolite dominant clastic deposit. The zone, up to 8 metres thick, occurs in mid-H-W horizon stratigraphy, west of the original Trumpeter discovery drillholes. Trumpeter Upper/Lower represents typical massive sulphide mineralization along the base of the H-W horizon (on top of the Footwall Andesite unit). The intersections, from 0.5 to 8.5 metres thick, vary from chalcopyrite-rich (up to 30 per cent) to mixed chalcopyrite (7-20 per cent) - sphalerite (5-10 per cent) - pyrite assemblages. The Upper/Lower designation refers to repetition due to faulting. Results of this new drilling has increased proven and probable geological reserves for the Trumpeter zone to 227,935 tonnes grading 3.1 grams per tonne gold, 66.7 grams per tonne silver, 4.1 per cent copper, 0.3 per cent lead and 4.4 per cent zinc (Assessment Report 24617).
Total reserves (proven and probable) as of January 1, 1996 were estimated at 11,150,400 tonnes grading 1.5 grams per tonne gold, 27.5 grams per tonne silver, 1.6 per cent copper, 6.1 per cent zinc and 0.3 per cent Lead (Information Circular 1997-1, page 8). Zinc recovery in 1996 was up dramatically to 88.3 per cent while maintaining a concentrate grade of 50.5 per cent. Copper production was lower because of a reduction in head grade. The higher grade Battle zone supplied a larger portion of the ore as the year progressed, starting with 9 per cent in January 1996 and finishing with 30 per cent in December (T. Schroeter, personal communication, 1997).
As of December 31, 1996, geological reserves in the Extension zone stood at 316,940 tonnes grading 0.9 gram per tonne gold, 35.4 grams per tonne silver, 1.1 per cent copper and 3.2 per cent zinc. The latest drill results indicate an improved potential for this zone of up to 1 million tonnes of copper-zinc ore with significantly increased grade. The large thickness of the massive sulphide is greater than in the Battle zone and similar to the western end of the H-W deposit, from which it may be a fault offset (Northern Miner, December 8, 1997).
Total geological reserves (proven and probable) as of December 31, 1996 were 12.3 million tonnes at 1.9 grams per tonne gold, 40.4 grams per tonne silver, 1.8 per cent copper and 7.8 per cent zinc (WWW http://westmin-resources.com/myrafall.htm, December 1997).
Mineable reserves estimated by the company, as of January 1, 1997, were 9,098,407 tonnes grading 1.6 per cent copper, 6.1 per cent zinc, 1.5 grams per tonne gold and 27.5 grams per tonne silver, sufficient for 8 years of production. In addition nearly 2 million tonnes of possible geological reserves have been outlined in several zones on the property. Battle zone ore, with head grades rising to 1.64 per cent copper and 5.4 per cent zinc, now makes up approximately 30 per cent of mill feed. The H-W zone accounts for approximately 70 per cent of current production (Information Circular, 1998-1, page 9).
In 1997, Westmin also drilled eleven core holes (aggregate depth of 5287 metres) from surface at the mine site to delineate the northwestern extension of the main H-W lens southeast of the Battle zone. The extension area had previously been drilled from underground but intercepts were poorly located for developing a reserve. The surface holes show that the H-W extension zone is far richer in zinc than had previously been thought. Its average grade is likely to be closer to that of the Gopher zone than the main H-W lens. One intercept is reported to have assayed 10.9 per cent zinc, 2.3 per cent copper, 1.3 per cent lead, 1.0 grams per tonne gold and 49.3 grams per tonne silver over 16.9 metres. As of December 1997, aggregrate proven and probable mining reserves were 8,057,756 tonnes grading 1.6 per cent copper, 7.5 per cent zinc, 0.4 per cent lead, 1.4 grams per tonne gold and 33.5 grams per tonne silver (Exploration in BC 1997, page 56). This reserve, plus measured and indicated resources totals 11,051,000 tonnes grading 1.79 per cent copper, 8.51 per cent zinc, 0.49 per cent lead, 1.81 grams per tonne gold and 46.4 grams per tonne silver (Boliden Limited 1997 Annual Report, page 52).
In January 1998, Westmin Resources Limited was taken over by Boliden Limited. The property is operated by Boliden Westmin Ltd., Myra Falls Operation. In December 1998, Boliden suspended production in order to rehabilitate underground workings and conduct maintenance work. The mill continued at half-capacity to process waste rock for backfill. Production resumed March 24, 1999.
As of January 1999, Myra Falls had a fully diluted mining reserve of 6,785,800 tonnes grading 7.9 per cent zinc, 1.5 per cent copper, 0.5 per cent lead, 1.5 grams per tonne gold and 36.8 grams per tonne silver (Exploration and Mining in BC 1998, page 48).
Total proven and probable reserves stand at 6.7 million tonnes averaging 7.7 per cent zinc, 1.5 per cent copper and 0.4 per cent lead, 1.4 grams per tonne gold and 34.9 grams per tonne silver. This includes a 28 per cent dilution factor. Of that amount, 1.9 million tonnes grading 3.3 per cent zinc, 1.5 per cent copper, 0.3 per cent lead, 1.7 grams per tonne gold and 25.4 grams per tonne silver are in the H-W deposit. The Battle deposit contains 3.5 million tonnes averaging 10.1 per cent zinc, 1.5 per cent copper, 0.4 per cent lead, 0.9 gram per tonne gold and 27.2 grams per tonne silver. The Gap zone contains 553,000 tonnes averaging 11.7 per cent zinc, 1.7 per cent copper, 1 per cent lead, 2.9 grams per tonne gold and 107.8 grams per tonne silver. Other deposits within the lower H-W horizon include: the Extension zone, which contains 211,000 tonnes averaging 4 per cent zinc, 1.1 per cent copper, 0.4 per cent lead, 0.8 gram per tonne gold and 33.8 grams per tonne silver; and the 43-Block zone, which holds 575,000 tonnes averaging 4.9 per cent zinc, 1.5 per cent copper, 0.4 per cent lead, 2.3 grams per tonne gold and 43.4 grams per tonne silver. Total measured and indicated reserves stand at 5.3 million tonnes averaging 7.7 per cent zinc, 1.6 per cent copper, 0.7 per cent lead, 2 grams per tonne gold and 56 grams per tonne silver (Northern Miner, June 28, 1999). Resources in the Marshall zone (092F 071), situated on the H-W horizon, stand at 320,000 tonnes averaging 7.6 per cent zinc, 0.7 per cent copper, 0.7 per cent lead, 2.5 grams per tonne gold and 105.6 grams per tonne silver. The zone remains open to the east, west and to the north (Northern Miner, June 28, 1999).
Boliden resumed production in March 2002; the mine was closed since December 2001 due to low metal prices.
The proven ore reserve published May 13, 2003 for the H-W and Battle/Gap zone was 6,267,000 tonnes grading 1.2 grams per tonne gold, 42 grams per tonne silver, 1.3 per cent copper, 7.4 per cent zinc and 0.6 per cent lead. The probable reserve was 2,080,000 tonnes grading 1.3 grams per tonne gold, 36 grams per tonne silver, 1.1 per cent copper, 4.6 per cent zinc and 0.5 per cent lead. The measured mineral resource was 1,991,000 tonnes grading 1.5 grams per tonne gold, 53 grams per tonne silver, 1.6 per cent copper, 9.4 per cent zinc and 0.7 per cent lead. The indicated mineral resource was 2,588,000 tonnes grading 1.9 grams per tonne gold, 68 grams per tonne silver, 1.1 per cent copper, 5.9 per cent zinc and 0.7 per cent lead and the inferred mineral resource was 2,478,000 tonnes (Boliden Annual Report, May 13, 2003 at http://www.sedar.com).
In 2003, Boliden re-established its exploration program at the mine, including the development of a 5-year exploration plan. A total of 35 targets have been identified and prioritized. Approximately 33,500 metres of underground drilling was completed.
In 2004, production remained steady at mine through a change in ownership from Boliden Westmin (Canada) Ltd to NVI Mining Ltd (a subsidiary of Breakwater Resources Ltd) in July. Approximately 8500 metres of core drilling was completed adjacent to the H-W and 43 zones now in production and a drill program targeting the Marshall East area was being considered by the company late in the year. Drifting toward the Marshall East zone to provide drilling stations was completed in 2003.
In 2005, about 36,000 metres of core drilling was to be completed by year's end to test the Extension zone west of the Battle-Gap zone and to test for extensions of the 43 Block and HW zone, and along the Marshall trend where significant potential for additional ore has been identified with previous drilling. Eight hundred metres of new underground development was completed across the Marshall trend in 2005 to provide for drill stations closer to targets.
The proven ore reserve published March 30, 2006 for the H-W and Battle/Gap zone was 4,952,000 tonnes grading 1.2 grams per tonne gold, 45 grams per tonne silver, and 1.1 per cent copper, 6.3 per cent zinc. The probable reserve was 1,048,000 tonnes grading 1.2 grams per tonne gold, 52 grams per tonne silver, 1.1 per cent copper, and 6.5 per cent zinc. The measured mineral resource is 5,386,000 tonnes grading 1.6 grams per tonne gold, 59 grams per tonne silver, 1.4 per cent copper, and 8.3 per cent zinc. The indicated mineral resource is 3,261,000 tonnes grading 2.1 grams per tonne gold, 72 grams per tonne silver, 1.2 per cent copper, and 6.9 per cent zinc (Breakwater Resources Ltd. Annual Information Form 2005, March 30,2006 www.sedar.com).
The combined Proven and Probable ore reserve published March 28, 2008 for the H-W and Battle/Gap zone was 5,835,000 tonnes grading 5.4 per cent zinc, 0.5 per cent lead, 1.0 per cent copper, 45 grams per tonne silver, and 1.3 grams per tonne gold. The combined Measured and Indicated resources were 6,323,000 tonnes grading 7.3 per cent zinc, 0.6 per cent lead, 1.3 per cent copper, 58 grams per tonne silver, and 1.6 grams per tonne gold. The Inferred resources were 3,777,000 tonnes grading 7.8 per cent zinc, 0.9 per cent lead, 1.0 per cent copper, 90 grams per tonne silver, and 2.2 grams per tonne gold. The combined Measured and Indicated resources includes the Proven and Probable reserves, but not the Inferred resources (Annual Information Form of Breakwater Resources Ltd. Year Ended December 31, 2007; released March 28, 2008; www.sedar.com).
October 29, 2008 Breakwater announced that operations would cease temporarily due to low commodity prices, but operations were maintained on a reduced level.
In 2011 Nyrstar, N.V. acquired Breakwater Resources Ltd. (Exploration and Mining 2011, page 65).
In April 2015 Nyrstar released updated Reserves and Resources for Myra Falls (News Release, April 29, 2015):
Nyrstar suspended mining activities at Myra Falls Operations at the beginning of the second quarter 2015. At that time the workforce was reduced, however work proceeded on the restoration and upgrading of power facilities and other infrastructure. Mine development planning focused on the western orebodies with exploration and definition drilling directed at those targets. Generally, exploration was successful, producing high grade intercepts as well as identifying untested targets.
In October 2015, Nyrstar halted investment at the mine, responding to a combination of low zinc prices, deficiencies in site infrastructure, planning, operation and maintenance practices and development of future mining areas. The suspension is part of a company-wide effort to preserve cash and mineral resources during a prolonged period of low commodity prices.
The mine commenced zinc production during September 2018 after the primary components of the restart scope of work had been completed, but had to suspend operations at the end of the fourth quarter of 2018 to address deficiencies. The company is currently working to address the necessary repairs and hopes to resume production in 2019.