Work History

The earliest exploration activity in the area was placer mining on Canadian Creek in 1911. The first lode claims, Tungsten and Nick cl (12624) were staked in 1917 by N. Hansen following identifications of huebnerite in the placer concentrates by the Geological Survey of Canada in 1916. Claims partially covering the porphyry were staked on numerous occasions for either tungsten or gold, including the BRC cl (57619) in July 1949 by H. Colley.

Restaked as Cat cl 1-23 (92201) in July 1965 by Casino Silver Mines Ltd. The company added Cat cl 24-42 (92764) in Sep/1965 and Cat cl 47-70 (95724) in Dec/1965. The claims were staked in conjunction with work on the nearby Bomber occurrence (Minfile Occurrence 115J 027). Casino performed soil sampling, mag and EM surveys in 1966 and 1967 for silver-lead veins but the focus quickly shifted to the bulk tonnage, open pit potential after soil geochemical surveys returned widespread anomalous copper and molybdenum values over an intensely altered and deeply weathered intrusive complex.

In late 1967, the Brynelson Group acquired control of Casino and performed grid soil sampling and mapping. The property was optioned to Brameda Resources Ltd in May/1969, and in the period to Aug/1970, the porphyry deposit was explored by detailed mapping, IP surveys and 11 275.2 m of BQ diamond drilling and 5 328.8 m of rotary drilling (84 holes total), largely financed by Quintana Minerals Corporation. Preliminary metallurgical studies were also completed. Although results were encouraging and a 45 tonne/day test mill was enroute to the property, all work terminated abruptly in Aug/1970 when Quintana withdrew financial support.

In 1973, Brameda exchanged its option for a 38.4% equity in Casino Silver Mines Ltd, after which Brameda merged with Teck Corporation Ltd. Later that year, Casino with financing from Teck, conducted gold geochemical and EM surveys, drilled 7 holes (1421.0 m) and added Rat, cl 1-44 (Y75586).

Although recognized as a major resource, the Casino property was inactive throughout most of the 1970s and early 1980s due to low copper prices. In 1985, the leached cap portion of the property was optioned to Archer, Cathro & Associates (1981) Ltd and explored by Permian Resources Ltd & Nordac Mining Corp, which conducted geochemical surveys, metallurgical testing and 6 018 m of bulldozer trenching directed toward heap leach gold potential.

Archer, Cathro optioned the entire property in Nov/1991 and transferred its interest to Big Creek Resources Ltd which added Cas cl 1-42 (YB36552) to the north and east; Dip 1-81 cl (YB36588) to the east and south; Cat cl 28, 30,32 and 34 (YB36999) to the northwest and F cl 1-49 (YB37252), G cl 1-32 (YB37300) and I cl 1-38 (YB37640) to the southwest between Dec/1991 and Sep/1992.

Big Creek Resources evaluated the gold potential of the deposit with 21 large diameter diamond drill holes (4 724.4 m) in 1992, before amalgamating with Pacific Sentinel Gold Corporation effective 1 Dec/92. At the same time, Pacific Sentinel acquired Casino Silver Mines Ltd as a wholly owned subsidiary, thus obtaining a 100% interest in the property subject only to a 5% net profits interest to Archer Cathro.

In Mar/1993, Pacific Sentinel commenced a $7.2 million diamond drilling program with the aim of fully delineating the deposit. In Aug/1993, an environmental baseline survey was completed on the A,B,C,D,E,F,G,H,I and Dip claims, and between March and November, 127 holes were drilled totaling 5 0 316 m.

In 1994, Pacific Sentinel completed an infill, delineation and geotechnical drilling program comprising 16 800 m of large diameter diamond drilling in 83 holes. In addition 34 geotechnical holes, totaling 2 896 m were completed for mine engineering design purposes. Following completion of the drilling program the company embarked on extensive metallurgical testing of several possible process options for the mineral zones. At the end of 1994, the company began pre-feasibility studies.

In Nov/1997 Pacific Sentinel merged with Consolidated North Coast Industries Ltd to form Great Basin Gold Ltd. In May/2000 Great Basin Gold optioned 55 claims (Casino "B" claims) located to the west which adjoin the neighbouring Ana claims to Wildrose Resources Ltd. Wildrose also undertook responsibility to file assessment work on the remaining claims which cover the actual Casino deposit. In 2000 Wildrose Resources drilled 4 diamond drill holes (531.57 m) on the optioned claims. The company followed up with prospecting and rock sampling in 2001.

In July 2002 Great Basin optioned the Casino deposit to CRS Copper Resources Corporation, a private British Columbia company focused on the acquisition, exploration and development of advanced stage copper properties. First Trimark Ventures Inc subsequently acquired CRS in May/2003 before changing its name to Lumina Copper Corporation. A plan of arrangement to restructure Lumina Copper Corporation into four separate companies was completed and announced in May/2005. Lumina Resources Corporation, which began trading on the Toronto Stock Exchange in May 2005, assumed operational control of the Casino Project.

In Sep/2006 Western Copper Corporation acquired Lumina Resources Corp and its option agreement covering the Casino property. In Jun/2007 Western Copper staked Vik cl 1 -188 (YC64893) to the south and east. In Jul/2007 the company initiated a pre-feasibility study of the property. In Aug/2007 Western Copper purchased Great Basin Gold's interests in the Casino property for $1 000 000.00 cash thus consolidating 100% control of the property with Western Copper. This agreement did not cover the Casino "B" claims which remained part of the adjoining Canadian Creek property (Minfile Occurrences 115J 101, 036 & 035).

Western Copper announced the results of positive pre-feasibility in Jun/2008. The study which included resource and reserve calculations, estimated an initial capital cost of $2.1 billion with production of 3.6 billion pounds copper, 320 million pounds molybdenum and 5.1 million ounces of gold over a 30 year mine life. An average mill throughput of 90,000 tonnes per day of sulphide ore was used in the calculation. During 2008 the company refurbished the camp facilities, drilled 3 diamond drill holes (1 163 m) and continued collecting baseline environmental studies.

In 2009, Western Copper completed a Quantec Titan 24 deep-penetration geophysical survey over the Casino deposit in order to identify zones of potential mineralization outside the area of currently defined mineralization. The geophysics program was followed-up with 37 diamond drill holes (10 850 m). Twenty-seven holes (6 616 m) were infill holes drilled to upgrade inferred and undefined material to measured and indicated classes.  The remaining 10 holes (4 327 m) targeted geophysical targets identified by the Quantec Titan geophysical survey.  
 
In 2010 Western Copper continued infill and delineation drilling. Forty-six exploration drill holes (12 046.2 m) were completed. An additional 16 drill holes (2 084.79 m) were collared for geotechnical and hydrogeological studies and one hole (153.92 m) was drilled for a water well. Between April and Jun/2010 Western Copper relogged all Pacific Sentinel core stored on the property in order to provide data for new lithology and alteration models and to group the geological units into four generalized rock groups.
 
On November 1, 2010 Western Copper released an updated NI 43-101 compliant resource estimate for the Casino Gold-Copper-Molybdenum project. The new estimate incorporated 26 000 m of new drilling performed by Western Copper since the resource estimate released as part of the Jun/2008 pre-feasibility study.
 
In Apr/2011 Western Copper released an updated pre-feasibility study for the Casino project. The study recommends that the Casino project be built as an open pit mine and a mill processing 120 000 tonnes per day of ore, resulting in the production of 14 913 975 grams (435 000 ounces) of gold, 106.2 million kilograms (234 million pounds) copper 5.9 million kilograms, (13 million pounds) of molybdenum and 54 856 000 grams (1.6 million ounces) of silver per year. The study estimated an initial capital cost of 2.13 billion and a mine production schedule of three years of preproduction followed by 20 years of commercial pit operations. The processing of low grade ores would extend commercial production an additional 3 years. The gold-rich leached cap would be mined separately using conventional heap leach technology that would begin in the first year of preproduction and continue until year 4 of commercial production.
 
 As part of the per-feasibility study consultants recommended building a new airstrip to service the Casino project.  In order to achieve this goal Western Copper staked Fly cl 1-12 (YD04375) approximately 14 km to the southwest along the southern branch of Dip Creek.
 
On June 23, 2011 Western Copper announced its intention to spin out various assets to two new subsidiaries. The result of this plan would result in the Casino project become the company’s main asset. On October 3, 2011 shareholders approved the asset spin out and a change in the company’s name to Western Copper and Gold Corporation. On October 5, 2011 the Supreme Court of British Columbia granted the final order approving the previously announced plan of arrangement.
 
In the fall of 2011 Western Copper and Gold began initial engineering studies required before initiating a feasibility study. In Jan/2012 the company began working on a feasibility study to bring the Casino project to production. The company continued working on the feasibility study through 2012.

In January 2013, Western Copper and Gold released a 43-101 compliant feasibility study.  See Capsule Geology for this resource estimate.

In 2019, Western Copper carried out a program of infill drilling, comprising 13,590 m in 72 holes. This program was designed to upgrade mineralization in the inferred resource category located along the margin of the deposit to the indicated category.

In 2020, the company completed a diamond drilling program comprising 12,007.54 m in 49 holes, targeting three main areas: the Gold, Northern Porphyry and Casino West zones. Drilling at the Gold Zone was designed to test for higher grade mineralization along the south and west boundaries of the deposit. Northern Porphyry zone drilling targeted potential northern extensions of the deposit. Drilling at the Casino West zone was designed to test for continuation of the deposit along the south flank of Canadian Creek.

In 2021, the company completed a diamond drilling program comprising 6,358.97 m in 22 exploration holes and 7 geotechnical holes.

In August, 2022, the company completed an updated Feasibility Study for the project.

Capsule Geology

The Casino deposit is one of the largest, highest grade porphyry deposits in Canada. It is located within the Dawson Range, a west-central portion of the Yukon-Tanana terrane. The Yukon-Tanana terrane is composed dominantly of metamorphic rocks inferred to be Devonian to Mississippian in age that has been intruded by numerous Mesozoic granitic bodies and plutons hosting copper, molybdenum and gold mineralization.

In the deposit area, Yukon-Tanana terrane rocks are intruded by the mid-Cretaceous Dawson Range batholith, and subsequent Casino Intrusions. The Dawson batholith measures an approximately 300 km long by 60 km wide and extends northwest of Carmacks to the Alaskan border and dominates the geology of the Dawson Range. At the Casino deposit, the batholith consists of undeformed granodiorite.
 
The Dawson Range batholith is in turn intruded by the Casino Plutonic Suite which is represented by fine- to medium-grained leucocratic granite, quartz monzonite and alaskite with associated aplite phases. The Casino Plutonic Suite is composed of stocks up to 18 km in diameter and is only exposed in the Colorado Creek (NTS 115 J/9) and Selwyn River (NTS 115 J/10) map areas. The Casino Plutonic Suite was originally thought to be Late Cretaceous (70 Ma) but work by Selby et al., (1999) indicates that although the Casino Plutonic Suite intrudes the Dawson Range Batholith, its age is indistinguishable (104.2 +/- 0.5 Ma, U-Pb zircon). Late Cretaceous igneous activity produced a northwest-trending belt of small stocks, one of which, the Patton porphyry intrudes the Casino Plutonic Suite rocks, producing the copper-gold-molybdenum mineralization present at the Casino deposit.

The Patton porphyry (72-74 Ma) represents two or more episodes of high-level intrusion of porphyritic hypabyssal dacite to rhyodacite. The main body of Patten porphyry, a few hundred metres across, occurs northwest of Patton Hill. Abundant Patton porphyry fragments occur in the adjacent microbreccia. The contacts between the Patton porphyry and the microbreccia are variable and range from sharply intrusive to gradational. Elsewhere, Patton porphyry forms many discontinuous dikes ranging from a few cm to 20 m wide; these cut Casino quartz monzonite and less commonly rocks of the Dawson Range batholith.
 
The Casino deposit is centred on an Upper Cretaceous-age, east-west elongated porphyry stock (Patton porphyry) that intrudes the Dawson Range Batholith and Yukon Tanana terrane country rocks. Intrusion of the stock into the older rocks caused brecciation of both the intrusive and surrounding country rocks along the northern, southern and eastern contact of the stock. Brecciation is best developed in the eastern end of the stock where breccia can be up to 400 m wide in plan view. To the west, and along the north and south contact, the breccia narrows gradually to less than 100 m. Only minor amounts of drilling have been completed at the western end of the stock and it is not known if breccia is present along this contact. Intruded into the stock and surrounding granitoids and metamorphic rocks are younger, non-mineralized dykes of similar composition to the older stock and a late diatreme  (or explosive breccia) which forms both a pipe-like body in the west and dyke-like body in the east.
 
Hypogene (or primary) mineralization occurs throughout the various alteration zones of the Casino deposit. It occurs mainly in the steeply plunging, in-situ contact breccia surrounding the Patton Porphyry intrusive plug and consists of recrystallization and exsolution of hydrothermal fluids from late Cretaceous magmas of the Prospector Plutonic Suite. Hydrothermal alteration consists of a potassic alteration zone about 450 m in diameter and a surrounding phyllic zone that extends 300 m into the Dawson Range Batholith. This alteration and the copper-molybdenum-gold mineralization are centered on the breccia. The breccia forms an ovoid band around the main porphyry body with dimensions up to 250 m. Based on diamond drilling completed to the end of 2011 the Casino deposit measures approximately 1.8 by 1.0 kilometres.

Primary mineralization consists of pyrite, chalcopyrite, molybdenite and minor huebnerite, and is concentrated in the phyllic zone along the inner side of a pyrite halo and is surrounded by weakly developed argillic and propylitic alteration. The deposit has not been glaciated and the high permeability associated with the brecciated and strongly altered mineralization has resulted in very deep weathering (up to 300 m) and the development of a classic stratified porphyry deposit consisting of: 1) a leached cap, followed by; 2) a narrow supergene oxide zone; and 3) a supergene sulphide zone lying above the main hypogene mineralization.
 
The leached cap (oxide gold zone) is gold-enriched and copper depleted due to supergene alteration processes as well as the lower specific of this zone relative to the other zones. It averages 70 m thick and is characterized by boxwork textures partly filled by jarosite, limonite, goethite and hematite. This weathering has completely destroyed rock textures and replaces most minerals with clay that is friable to the touch and often stained yellow, orange and/or brown by iron oxides.
 
The supergene oxide zone is poorly understood and exists as a few perched bodies within the leached cap. It is copper-rich and contains trace molybdenite and likely formed due to more recent fluctuations in the water table.  Where present the zone averages 10 m thick and can contain chalcanthite, malachite, brocanthite, with minor azurite, tenorite, cuprite and neotocite. The zone is thought is thought to be related to present day topography and is best developed where oxidation of early secondary copper sulphides occur above the water table, on well drained slopes.

The supergene sulphide (copper) zone occurs in an up to 200 m-deep weathered zone below the leached cap and above the hypogene mineralization. It has an average thickness of 60 m and is in part controlled by the distribution of pyrite, fracture density and by the erosion surface at the time of leaching. The high pyrite content of the phyllic zone promotes leaching; thus, secondary enrichment zones are thicker near the contact of the potassic and phyllic alteration zones. Copper grades in the supergene sulphide zone are almost double the copper grades in the Hypogene (0.43% copper versus 0.23% copper).Grain borders and fractures in chalcopyrite, bornite and tetrahedrite may be altered to chalcocite, diginite and/or covellite. Chalcocite also locally coats pyrite grains and clusters, and may extend along fractures deep into the hypogene zone. Molybdenite is largely unaffected by supergene processes, other than local alteration to ferrimolybdite. In drill core the supergene sulphide zone is generally broken with decreasing clay alteration and weathering is “stained” dark blue to gray.
 
The hypogene zone lies under the supergene sulphide zone. Its exact thickness is not yet known as mineralization was present at the bottom of the deepest drilled hole; over 600 m from surface. Hypogene mineralization (or primary) consists of pyrite, chalcopyrite and lesser molybdenite.
 
Early exploration in the area was centred on the silver-lead vein discovered at the Bomber occurrence (Minfile occurrence # 115J 027) located approximately 2 km to the south. Soil sampling, geological mapping, trenching and various geophysical surveys during the mid-1960’s led to a large diamond/rotary drilling program in 1969-70. In Dec/69 Casino Silver Mines announced the discovery of a potential billion plus tonne low-grade, copper-molybdenum deposit. Although the project has lain dormant at times all exploration work since 1969 has been aimed at bringing the deposit into production.  
 
A major breakthrough in the projects history occurred in 1991 when Archer, Cathro and Associates (1981) Ltd re-assayed Casino core for its gold content. The realization that the deposit might hold economic amounts of gold led Archer, Cathro to option the property in Nov/91. The company immediately optioned the property to Big Creek Resources which carried out a large diamond drill program in 1992. In Dec/92 Big Creek Gold amalgamated with Pacific Sentinel Gold to try and bring the deposit into production.
 
In the spring of 1994 Pacific Sentinel released a historic resource estimate (i.e. not NI-43-101 compliant) of 558 million tonnes containing 1.43 billion kilograms of copper, 184.79 million grams of gold and 140 million kilograms of molybdenum  from the leached cap, supergene (oxide and sulphide) and hypogene zones. Included in this calculation is an expanded high grade open pit mineable core of 90 million tonnes grading 0.4% copper, 0.05% molybdenum and 0.48 g/t gold. (Yukon Exploration and Geology 1993, p. 4 and Pacific Sentinel Gold Corp. 1993 Annual Report p. 4).
 
The property saw intermittent work through the 1990’s and early 2000’s. In Jan/2003 CRS Copper Resources Corp and First Trimark Ventures Inc released a National Instrument 43-101 compliant technical report (under the name Lumina Copper Corp) which contained individual resource estimates for the leach cap, supergene oxide, supergene sulphide and hypogene zones (see Reserves section for details). In Feb/2004 Lumina Copper Corp released updated resource figures for the four zones employing copper equivalent (Cu EQ) grades.
 
Following Western Copper Corp’s purchase of the property in Sep/1996 the company set about consolidating the property under one owner. In Aug/2007 Western Copper initiated a pre-feasibility study of the Casino property which was released in Jun/2008 (see Reserves section). This study updated the resource figures for the four zones and introduced further refinements to the statistical analysis used to estimate grade and tonnage. This led to an overall decrease in the tonnage reported for the measured and inferred classes when compared to values reported in the 2004 resource estimate.
 
The 2008 pre-feasibility study also included the first NI 43-101 mineral reserve estimate for the Casino project. The reserve estimate is based on pit design and the mine production schedule developed in the pre-feasibility study and is reported as a mill ore reserve and heap leach reserve. The heap leach reserve tonnage figure is higher and the gold grade is lower than that reported in the resource estimate. This difference attributed to the lower recoveries and higher tonnages required to mine the heap leach cap. The mill ore reserve tonnage figure and the overall gold and copper grades are lower that the resource estimates. This difference is attributed to the actual mining plan as some ore reported in the resource calculation will not actually be mined.
 
The 2008, 2009 and 2010 diamond drilling programs were designed to increase the property’s resources/reserves. On November 1, 2010 Western Copper announced an updated resource estimate for the Casino project. The estimate employed the results of 26 000 m of core drilled in 2008, 2009 and 2010 and reinterpretation of the geology which included the re-logging of 90 000 m of core originally drilled by Pacific Sentinel Gold Corp. The immediate goal of increasing the near-surface supergene sulphide zone was achieved with the size of this zone increasing from 133 million tonnes to 252 million tonnes at the measured and indicated level. Other noteworthy increases were obtained in the inferred resource of the supergene oxide, supergene sulphide and hypogene zones which increased from 232 million tonnes to 1 696 million tonnes. Current resources at the Casino project employing a 0.25% copper equivalent (Cu EQ) cutoff, total 1.06 billion tonnes of combined supergene oxide, supergene sulphide and hypogene mineralization at the measured and indicated level.  The leached cap/oxide gold zone (employing a 0.40 g/t gold cutoff) currently hosts an additional 32 million tonnes of combined measured and indicated resources.
 
The 2011 pre-feasibility study updated and revised the various parameters used in the earlier 2008 pre-feasibility study. As part of the study an updated mineral reserve was calculated for the Casino project. The reserve estimates differ from the resource estimates because reserves are based on the mine and plant production schedule. 
 
As of May/2011 the Casino project hosts a mill ore reserve of 975.8 million tonnes grading 0.202% copper, 0.238 g/t gold, 0.0229% molybdenum and 1.73 g/t silver. The heap leach reserve is an additional 81.6 million tonnes at 0.37 g/t gold, 2.55 g/t silver and 0.041% copper.  The mill ore reserve increased approximately 7% over the 2008 reserve figure, however this figure does not take into account the approximately 600 percent increase in inferred resources. The heap leach reserve has increased approximately 4.7 % over the 2008 reserve figure.

In January 2013, Western Copper and Gold released a 43-101 compliant feasibility study. The deposit hosts a total of 965 million tonnes of proven and probable mill ore reserves and 157 million tonnes of proven and probable heap leach reserves. Based on the economic analysis, the Property will produce the following over the life of the mine from heap leach and flotation:  Gold: 178 tonnes (5.72 million ounces), silver: 941.2 tonnes (30.26 million ounces), copper: 1.6 million tonnes (3.58 billion pounds) and molybdenum: 147,000 tonnes (325 million pounds).

The mineral resource was divided into two zones: the Supergene and Hypogene Zone (or Mill Resource) and the Leached Cap/ Oxide Gold Zone (Heap Leach Resource).

RESOURCE: The Supergene and Hyphogene Zone is tabulated at a 0.25% copper-equivalent cutoff grade. Measured and indicated supergene (oxide and sulphide) and hypogene resource are listed as 1.057 billion tonnes at 0.2% copper, 0.23 g/t gold, 0.022% molybdenum, and 1.71 g/t silver. The Inferred resource is an additional 1.7 billion tonnes at 0.14% copper, 0.16 g/t gold, 0.019% molybdenum, and 1.37 g/t silver.

The Leach Cap/ Oxide Gold zone contains potential heap leach ore and is tabulated at a 0.25 g/t gold cutoff grade. Measured and indicated heap leach ore amounts to 84 million tonnes at 0.04% copper, 0.4 g/t gold, and 2.57 g/t silver. Inferred resource is an additional 17 million tonnes at 0.01% copper, 0.31 g/t gold, and 1.93 g/t silver.

RESERVES: Based on the mine plan and production schedule, the Mill Ore Reserve (proven and probable) is calculated as 965.2 million tonnes at 0.20% copper, 0.24 g/t gold, 0.023% molybdenum, and 1.74 g/t silver. The Heap Leach Reserve (proven and probable) adds up to an additional  157.5 million tonnes at 0.29 g/t gold, 0.036% copper and 2.21g/t Ag.

Assessment Reports that overlap occurrence