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The Golden Mile Property
The Golden Mile Property is located in the Cedar Mountains in Mineral County, Nevada, approximately 88.5 km (55 miles) northwest of Tonopah.
Golden Mile is 100% controlled by Columbus Gold, subject to underlying royalties.
Columbus Gold is seeking a partner to option in at the Golden Mile Property.
Golden Mile is underlain by carbonate rocks of the Triassic Luning Formation along with siltstone, sandstone and minor carbonate rocks of the Jurassic Dunlap Formation. The Dunlap Formation has been intruded by Mesozoic granodiorite and dikes of quartz porphyry. Mineralization is hosted in calc-silicate altered intrusive rocks and, to a lesser extent, in Dunlap clastic and limy rocks along an easterly trending, arcuate, often steep and brecciated contact between the sediments and intrusive. The zone has a known strike length in excess of 730 m (2,400 ft) and has widths locally up to 300 m (1,000 ft). Low-grade mineralization continues to the north under post-mineral Tertiary andesite flows and felsic tuffs and remains open in that direction.
Gold mineralization, along with erratic copper/magnetite mineralization, primarily hosted in carbonate rocks, occurs within calc-silicate (diopside/garnet/epidote) replacement zones often characterized by breccia and/or calcite/quartz stockworks. These zones appear to be along northeast trending fractures and shears cutting both sediments and intrusive. Mineralization is very erratic both in grade and thickness along strike and dip within the fracture system.
Two preliminary mineral inventories, neither of which are 43-101 compliant, have been calculated at Golden Mile. The first yielded 2,400,000 tons at a grade of 0.064 opt gold* using a tonnage factor of 12.5 tons and a cutoff of 0.020 opt gold. The second was carried out with variations in techniques of handling internal waste and a 0.010 opt gold cutoff and yielded 3.6 Mt of 0.038 opt gold*. The mineralization is thought to be minable by open pit methods. The erratic nature of the mineralization is very difficult to model and computer-aided calculations will be necessary in the future to better estimate the size of the resource.
Four preliminary bottle roll tests were carried-out by Kappes-Cassiday in 1982 to evaluate the metallurgical response of the ore. Recoveries varied from 81.4% to 87% on -6 mesh material.
Golden Mile has a long exploration history. Early work was completed in the 1970's by Colorado Energy Corp. and Standard Slag Co. which drilled 7 air-track holes totaling 81 m (268 ft) in an area of historical magnetite/copper skarn workings, now known as the main zone. The best intercept was 7.6 m (25 ft) of 0.25 opt gold at surface.
The project was controlled by Elmwood Resources from 1982-1988 and they performed a ground magnetic survey and drilled 18 shallow air-track holes totaling 347 m (1,141 ft) in the main zone and in altered rocks to the west-northwest of the main zone. Their best intercept was 14 m (46 ft) of 0.101 opt gold near surface. Battle Mountain Exploration Co. acquired the property in 1988 and performed ground magnetics, VLF and drilled 29 RC holes totaling 3,550 m (11,650 ft) in the main zone and along the intrusive contact to the northeast. They also drilled several vertical holes into and through the volcanic rocks north and east of the main zone. Their drilling intersected ore-grade mineralization including 29 m (95 ft) of 0.580 opt gold hosted in weak skarn, hornfels sediments and in altered intrusive at the sediment contact. They extended the zone of mineralization to the northeast for some 90 m (300 ft) under volcanic cover.
USMX drilled an additional 15 RC holes totaling 1,487 m (4,880 ft) in 1993 testing down-dip extensions of the mineralization intersected in the Battle Mountain Exploration holes. Results included: 12 m (40 ft) of 0.075 opt gold, 13 m (45 ft) of 0.124 opt gold, 4.5 m (15 ft) of 0.344 opt gold and 38 m (125 ft) of 0.028 opt gold.
Battle Mountain Gold Corp. held the project in 1996 and 1997 and completed another ground magnetics survey while re-logging several of the earlier drill holes but performed no drilling. Between 1998 and 2000 Teck Resources completed rock sampling, magnetics, IP and CSAMT and drilled five deep angle RC holes targeting geophysical anomalies. Several of their holes intersected thick zones of low-grade gold up to m (1,500 ft) to the northeast of the main workings.
Columbus Gold acquired the project in 2004. The project area was re-mapped and 28 rotary drill holes were completed in two phases of drilling in 2006 totaling 4,320 m (14,170 ft). The drill program was designed to test down-dip and strike extensions of better grade mineralization from earlier drilling and for possible extensions of mineralization under volcanic cover, primarily to the north and northeast. Drill holes MI-6 and MI-12 intersected 25 ft (7.5 m) of 0.12 opt gold and 30 ft (9 m) of 0.410 opt gold respectively. Several other holes cut thick ≥ 100 ft (≥ 30 m), continuous zones of low-grade (± 0.01 opt) gold mineralization.
Roscan completed a drilling program in 2011 consisting of a total of 958.9 m (3,146 ft) in five diamond core holes. Four of the holes were drilled as twin holes to reverse circulation rotary (RC) holes drilled by previous explorers to compare assay results and to determine controls on gold mineralization. One hole was drilled to test a mapped north-northwest trending shear zone.
The drilling intersected 6.1 m averaging 46.403 gpt gold (20 ft averaging 1.353 oz/ton) in hole GMC002, which twinned a previous reverse circular hole that intersected 9.1 meters averaging 46.97 gpt gold (30 feet averaging 1.37 oz/ton). High-grade gold mineralization is concentrated in iron oxide veinlet zones that represent weathered pyrite veinlet zones that trend north-northwest within calcareous sandstone and quartz diorite.
The drill program was designed to determine which structures host the gold in the Golden Mile Property, along with the distribution and trend of the mineralization in properties for delineating a reserve. Based upon logging of the core, anomalous to ore-grade mineralization is associated with calcite-pyrite ± quartz veinlets and semi-massive pyritic zones in calcareous sandstone and quartz diorite. The calcite-pyrite ± quartz veinlets are generally less than 2 cm thick and the pyritic zones are generally 2 to 10 cm thick. The most common orientation of both the veinlets and pyritic zones are 25° to Core Axis, suggesting a northwest orientation to gold mineralization.
Golden Mile is a large mineral system that remains open on strike and at depth with numerous ore-grade intercepts. Considerable potential remains to enlarge the reserve with further drilling. The gold zone remains open at depth and along strike particularly to the northeast where several widely spaced holes have encountered low-grade gold mineralization over thick intervals.
*Caution: A qualified person has not done sufficient work to classify the historical estimates contained herein as current mineral resources. Columbus Gold is not treating the historical estimates as current mineral resources and the historical estimates should not be relied upon.
John Prochnau B.Sc. (Mining Engineering), M.Sc. (Geology), and Technical Director of Columbus Gold is the Qualified Person under National Instrument 43-101, who reviewed and approved the contents of this section respecting the Columbus Gold drilling and exploration work at the Golden Mile Property.
John Lukens, CPG #11413, a qualified person under National Instrument 43-101, has prepared or supervised the scientific or technical information respecting the Roscan drilling at the Golden Mile Property.
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