Virtual Museum ID: 19-D1-02
Strongly hornfelsed andesite stockworked by pyrite-rich, chalcopyrite-poor veining. Low-grade or or waste (~0.1 - 0.15% Cu) from Main Zone deposit. From eastern Main Zone pit area, approximately 300m east of source Main Zone granodiorite stock.
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Original Collection:Smithers Exploration Group (SEG)
Sub Collection:Huckleberry Mine
Virtual Museum ID:19-D1-02
Date Added to VM:2019-02-21
Sample Origin:Huckleberry Mine, BC
Specific Site:Main Zone Deposit
Datum:09 (NAD 83)
VM Category:Ore Sample
Primary Features:Andesite/Hg ore
Primary Mineral Formula:Hg
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:Bulkley Plutonic Suite
Geological Period:Upper Cretaceous
Stratigraphic Age:Lower Jurrasic >~82 Ma
Geological Terrane:Stikine, Plutonic Rocks
Minfile ID:093E 037
The Huckleberry mine is located between Tahtsa Reach and Sweeney Lake on Huckleberry Mountain, about 100 kilometres south-southwest of the community of Houston. Relief is moderate to steep on the property with a maximum difference in elevation of
approximately 700 metres, from a variable elevation of 853 metres on Tahtsa Reach, to 1526 metres on HuckleberryMountain.
The southern slopes of Huckleberry Mountain have attracted mineral exploration for close to fifty years owing to the gossans and surface occurrences of copper-bearing minerals. Portions of the area have accordingly been explored by geochemical, geophysical and diamond drilling surveys. As a result of these surveys, two zones of mineralization were identified. The first of these, the Main Zone, was explored in several separate campaigns by various operators during the period 1962 to 1994. The East Zone was discovered during the course of site investigations in 1993, and was further explored from 1993-97. These programs led to the development of a mineral resource of 53.7 million tonnes grading 0.455 per cent copper, 0.013 per cent molybdenum and 0.06 gram per tonne gold at a 0.30 per cent copper cut-off grade in the Main zone, and 108.4 million tonnes grading 0.484 per cent copper, 0.014 per cent molybdenum and 0.055 gram per tonne gold in the East zone. Plant construction began in 1996, and mining operations began in the East Zone Pit in 1997. Development of the Main Zone Pit began in 1999. Mining operations were scheduled for completion in 2007, but the mine life has been extended until 2010 with the resources developed in the Main Zone Extension (MZX) portion of the deposit (ca. 2007, Assessment Report 29422).
At the Huckleberry deposit, porphyry copper and molybdenum mineralization is associated with a near elliptical stock of Upper Cretaceous age granodiorite porphyry (Bulkley Plutonic Suite) measuring approximately 670 by 425 metres. The stock intrudes fine grained crystal tuff of the Lower-Middle Jurassic Hazelton Group. Tuffs adjacent to the intrusion have been hornfelsed.
Mineralization consists of chalcopyrite and minor molybdenite in fractures, principally in the hornfelsed volcanics but also in the stock. Minerals accompanying chalcopyrite are quartz, orthoclase and pyrite with probably later calcite, gypsum and zeolite. Magnetite occasionally accompanies chalcopyrite. Disseminated chalcopyrite also occurs. Molybdenite usually occurs with quartz in hairline fractures. The mineralization generally occurs around the stock contact but the extent outward from the contact and the grade vary greatly. The best mineralization occurs on the east side of the stock. Potassic, pyrite and chlorite alteration haloes surround the stock.
A feasibility study in 1974 by Kennecott/Granby stated that there was a mining reserve of 77,647,760 tonnes grading 0.41 per cent copper, 0.01 per cent molybdenum and 1.50 grams per tonne silver at a 1.11:1 waste-to-ore strip ratio. Within this reserve lies a near-surface high-grade zone of 14,332,180 tonnes grading 0.55 per cent copper (George Cross News Letter No.189 (September 30) 1992). Estimated reserves in 1993 for the Main zone were 31 million tonnes grading 0.52 per cent copper (Information Circular 1994-1, page 12).
An eight-hole evaluation of the East zone, discovered by the drilling of a water quality monitoring well 1219 metres from the Main zone, was completed in 1993. The area of mineralization measures 182 by 60 by 121 metres deep that is open on all sides and to depth (Northern Miner - May 3, 1993). At a cut-off grade of 0.30 per cent copper, the company reported total mineable reserves at 91.2 million tonnes grading 0.52 per cent copper, 0.014 per cent molybdenum, 0.06 gram per tonne gold and 2.8 grams per tonne silver. Reserves for the Main and East zones are reported to be 30.9 million tonnes grading 0.48 per cent copper, 0.066 gram per tonne gold, 2.17 grams per tonne silver and 0.013 per cent molybdenum; and 60.3 million tonnes grading 0.536 per cent copper, 0.063 gram per tonne gold, 3.1 grams per tonne silver and 0.014 per cent molybdenum, respectively (Information Circular 1995-1, page 13).
The ore zones at Huckleberry are enclosed by an easterly oriented zone of alteration approximately 4 kilometres long and 1 to 2 kilometres wide. The Main zone occurs along the eastern periphery of a sub-circular stock located in the western part of the alteration zone and is further centred on an apophysis of the stock. Most of the mineralization occurs in an arc measuring 500 by 100 metres. The East zone occurs within and surrounding a similar porphyritic stock in the eastern part of the system and is approximately 900 by 300 metres and remains open at depth. The East zone appears to be centred on an apophysis of the East zone.
In 1994, New Canamin calculated the Main zone to contain a fully diluted in situ reserve of 53.7 million tonnes grading 0.445 per cent copper, 0.013 per cent molybdenum, 0.06 gram per tonne gold and 2 grams per tonne silver, based on a 0.30 per cent copper cut-off; and the East zone to contain an in situ reserve of 108.4 million tonnes grading 0.484 per cent copper, 0.014 per cent molybdenum, 0.055 gram per tonne gold and 3 grams per tonne silver at a cut-off grade of 0.30 per cent copper (CIM Special Volume 46, page 313).
The Huckleberry deposit will be mined by two open pits, the Main zone and the East zone. Planned mill throughput is 15,500 tonnes-per-day for the East zone and 14,000 tonnes-per-day for the Main zone, producing a total of 27,300 tonnes of copper annually over the anticipated 17-year mine life (Information Circular 1996-1, page 11).
In 1962, mineralization was first discovered by Kennco Explorations, which explored the area between 1962 and 1971. In 1972, the property was optioned to Granby Mining, which proved up the Main zone by means of drilling and metallurgical tests.
The East zone deposit was discovered in early 1993, after New Canamin Resources Ltd. optioned the property from Kennecott Canada a year before. New Canamin became sole owner of the project in 1994, and Princeton bought the company in July 1995. A feasibility study was finished in September, and a final production decision was issued the following June. Mineable reserves reported in 1995 were 26.82 million tonnes grading 0.48 per cent copper, 0.07 gram per tonne gold, 2.17 grams per tonne silver and 0.013 per cent molybdenum for the Main zone, and 72.71 million tonnes grading 0.52 per cent copper, 0.06 gram per tonne gold, 3.1 grams per tonne silver and 0.014 per cent molybdenum for the East zone (Exploration in British Columbia 1996, page A15).
In December 1995, the mine received a project approval certificate for the development of the mine. Site development began in March 1996 and startup is planned for September 1997. Mine construction began in 1997 at budgeted capital cost of 137 million dollars. The mine will process 16,500 tonnes of ore per day for a planned 16-year mine life. The mine was officially opened on October 1, 1997.
Based on a feasibility study prepared by H.A. Simons Ltd., the combined geological resource of the two deposits (Main and East zones) is 162 million tonnes grading 0.47 per cent copper and 0.014 per cent molybdenum. Based on a 0.30 per cent copper cut-off grade, total mineable reserves (includes proven and probable reserves scheduled in the mining plan) are calculated to be 90,372,500 tonnes grading 0.513 per cent copper, 0.062 gram per tonne gold, 2.812 grams per tonne silver and 0.014 per cent molybdenum. Mineable reserves (includes proven and probable reserves scheduled in the mining plan) for the East zone are 66,131,500 tonnes grading 0.523 per cent copper, 0.061 gram per tonne gold, 3.043 grams per tonne silver and 0.014 per cent molybdenum. Mineable reserves (includes proven and probable reserves scheduled in the mining plan) for the Main zone are 24,241,000 tonnes grading 0.484 per cent copper, 0.066 gram per tonne gold, 2.181 grams per tonne silver and 0.013 per cent molybdenum. Both the Main and East zone deposits will be mined by open-pit methods with a waste-to-ore ratio, including overburden, at a relatively low 1:1 (Princeton Mining Corporation 1996 Annual Report, page 5).
Imperial, as operator, owns 60 per cent of Huckleberry, and the Japan Group, a consortium which consists of Mitsubishi Materials Corporation, Marubeni Corporation, Dowa Mining Co. Ltd. and Furukawa Co., owns 40 per cent.
In 1998, ore milled amounted to 6,547,500 tonnes, averaging 0.632 per cent copper, from which 36,800,000 kilograms of copper and 248,000 kilograms of molybdenum were produced. Mineable reserves on January 1, 1999 were 80.754 million tonnes grading 0.501 per cent copper, 0.061 gram per tonne gold, 2.73 grams per tonne silver and 0.014 per cent molybdenum based on a copper price of US $1.00 per pound and a cut-off grade of 0.30 per cent copper (Exploration in British Columbia 1999, page 22). Ore mined to date is from the East zone starter pit which will be completed in 2000. The Main zone pit, 600 metres west of the East pit, has been stripped of overburden and its production will be blended with East pit ore in 1999.
The Northern Miner (June 7, 1999) reports mineable reserves at the end of 1998 at 74.7 million tonnes grading 0.51 per cent copper and 0.014 per cent molybdenum, 0.06 gram per tonne gold and 2.82 grams per tonne silver, at a stripping ratio of 0.93 to 1.
In the East pit, ore is derived 85 per cent from Hazelton Group andesite and 15 per cent from a dike, 40 metres wide, emplaced along an ore-controlling 110 degree striking fault. The dike is an offshoot of an 82 Ma biotite granodiorite stock which metamorphosed Hazelton Group andesite to biotite hornfels. Best copper grade occurs in the granodiorite dike and in hornfels on the south (footwall) side of the controlling fault.
In 1998, the Huckleberry company drilled seven exploration holes in a 700 metre semicircular arc around the west side of the Main stock. A hole near the south contact of the stock intersected a zone of secondary copper enrichment including chalcocite and native copper that grades 0.8 per cent copper over the initial 27 metres of the hole, and then continued in primary mineralization that averages 0.4 per cent copper (Exploration in British Columbia 1998, page 23).
In April 1999, Imperial Metals reduced its mineable reserves in light of the current copper price. The Main zone reserves are 16 million tonnes grading 0.51 per cent copper (cf. 24 million tonnes grading 0.484 per cent copper). The East zone reserves are being revised.
Mining of the East zone starter pit was completed in November, after supplying 76 per cent of the total ore milled during 1999. Pre-stripping of the Main zone was carried out throughout the year in preparation for full scale mining of ore and waste from this pit, beginning in November. Mill feed is scheduled to come from the Main zone for years 2000 and 2001. Overburden stripping of the East zone pushback is scheduled to begin in 2001 in anticipation of a return to full scale mining from this pit later that year.
A complete review of the proven and probable ore reserves was completed in late 1999 using updated topographic surveys and operating costs. Copper prices of US $0.70 per pound for the Main zone and US $1.00 per pound for the East zone were used for the pit optimization process. Proven and probable ore reserves as of December 31, 1999 are tabled below:
In the late fall of 1999, a geophysical survey was conducted over an area west of the tailings dam. Detailed geological mapping in the East zone pit during 1999, combined with previous geophysical and geochemical work identified two exploration target areas. These target areas will be drilled in 2000, testing possible ore extension to the northeast and southwest of the East zone pit.
Total probable reserves as of December 31, 2000 are 56,498,000 tonnes grading 0.494 per cent copper, 0.014 per cent molybdenum, 0.059 gram per tonne gold and 2.805 grams per tonne silver at a strip ratio of 0.66. This total includes 46,169,000 tonnes grading 0.488 per cent copper, 0.014 per cent molybdenum, 0.056 gram per tonne gold and 2.925 grams per tonne silver at a strip ratio of 0.73 and cut-off copper grade of 0.26 per cent in the East zone; and 10,329,000 tonnes grading 0.521 per cent copper, 0.014 per cent molybdenum, 0.071 gram per tonne gold and 2.269 grams per tonne silver at a strip ratio of 0.34 and cut-off copper grade of 0.35 per cent in the Main zone (Imperial Metals Corporation 2000 Annual Report).
The East zone probable ore reserve, as of December 23, 2002, is 36,719,000 tonnes grading 0.489 per cent copper, 0.013 per cent molybdenum, 0.056 gram per tonne gold, and 2.884 grams per tonne silver with a cut-off grade of 0.26 per cent copper and a strip ratio of 0.55:1 (http://www.imperialmetals.com, December 30, 2003).
In 2004, a large exploration program consisting of 8153 metres helped to identify a new potential deposit (Northwest Target), directly north of the Main zone pit. At present, the mine life is estimated to extend until 2007.
Probable reserves in the East zone as of December 31, 2004 are 19,435.000 tonnes grading 0.529 per cent copper, 0.015 per cent molybdenum, 0.059 gram per tonne gold and 2.982 grams per tonne silver at a cut-off of 0.26 per cent copper, (2005 Annual Information Form (http://www.imperialmetals.com/i/pdf/AIF2005-Mar17.pdf)).
Exploration drilling of an area northwest of the Main zone, named the Main Zone Extension, began in 2004 and continued with an additional 6388 metres in 2005.
In 2010, Imperial Metals Corp. announced updated reserves and resources:
Reserves and Resources for the Main Zone Optimization pit as of December 31, 2014:
(Imperial Metals Corporation Annual Information Form 2014 and Technical Report on the Main Zone Optimization Huckleberry Mine, November 22, 2011).
Mine life was extended to the year 2022 (Imperial Metals Corporation Annual Information Form 2014).
In August 2016, Imperial Metals Corporation ceased operations at Huckleberry and placed it on care and maintenance.