Corvus Expands Resource at North Bullfrog (Nevada)
Corvus Gold Inc. has released the results from its follow-up resource expansion program on its North Bullfrog project near Beatty, Nev. The updated independent estimate has expanded the district-wide indicated gold resource to 182,000 contained ounces at an average grade of 0.37 gram per tonne, plus an additional inferred gold resource of 1.41 million contained ounces at an average grade of 0.28 g/t, both at a cut-off grade of 0.20 g/t gold. This new, much larger resource reflects a major new discovery in the northern part of the company’s land area which consists of three deposits separated by large undrilled areas. In addition, some of the resource areas contain higher grade resources as well as high-grade vein systems which could be targets for early mining. The company has began acquiring the necessary information required for completion of a preliminary economic assessment, as well as designing and permitting a major follow-up grid drilling resource expansion program which will focus on both the bulk-tonnage and high-grade vein potential of the area.
NORTH BULLFROG ESTIMATED INDICATED AND INFERRED RESOURCE
(using a 0.20 g/t gold cut-off grade)(i)
Grade
greater than cut-off Contained
Tonnes greater
Resource than cut-off Gold Silver Gold Silver
category (tonnes) (g/t) (g/t) (oz) (oz)
Indicated 15,230,000 0.37 0.44 182,577 215,187
Inferred 155,630,000 0.28 0.84 1,410,096 4,212,532
(i) Mineral resources which are not mineral reserves do not have
demonstrated economic viability. The estimate of mineral resources
may be materially affected by environmental, permitting, legal,
marketing, or other relevant issues.
Jeff Pontius, chief executive officer of Corvus, stated: “We are extremely pleased with the very large expansion in the estimated resources at our North Bullfrog project and the potential that it indicates for further growth of this major new Nevada gold discovery. In addition to its increased size, the new resource is dominantly oxidized rock which has shown high gold recoveries in initial bottle roll tests. These early positive metallurgical results are currently being followed up with large-diameter column tests which will help evaluate the potential for low-cost run of mine, heap leach processing for gold extraction. The metallurgical results coupled with a geometry which may allow a very low strip ratio greatly enhance the project’s development potential. The North Bullfrog project is truly emerging as a major catalyst for the future evolution of Corvus into a premier North American gold company.”
Bulk tonnage resource
The resource update is focused on four of several targets in the North Bullfrog district, all of which remain open with potential to grow significantly. The primary host unit for the majority of the resource is a thick, oxidized, shallowly dipping volcanic unit which is commonly exposed at surface, thereby offering the potential for very low strip ratio. The continuity of the mineralization within the primary host unit is considered to be very good, and there is a high probability that the resource will increase with future step-out and infill drilling around the current widely spaced holes. In addition, the individually reported deposits are separated by undrilled areas which have projections of the favourable host unit between them, and which could therefore offer additional potential for resource expansion. Approximately 57 per cent of the current estimated resource is oxide material occurring at surface, which has returned highly encouraging cyanide bottle roll test results suggesting potential for low-cost heap leach recovery. Continuing metallurgical work is focusing on evaluating the potential of the bulk tonnage oxide deposits for heap leaching and, in particular, coarse run-of-mine material. The North Bullfrog property has a large number of areas that the company believes would be suitable for a large heap leach operation as well as ready access to key infrastructure and water.
High-grade potential
Drilling at the North Bullfrog project has returned a number of high-grade drill intersections similar to the historic high-grade veins that were mined seven kilometres to the south in the main Bullfrog district. Several high-grade gold and silver veins have been encountered in a number of areas, such as Yellowjacket (6.1 metres at 11.9 grams per tonne gold and 8.8 g/t silver), Mayflower (9.1 m at 7.18 g/t gold and 15.2 m at 2.87 g/t gold) and Connection (6.1 m at 2.67 g/t gold and 15.2 m at 2.44 g/t gold). As part of its follow-up grid drilling program, the company will be targeting high-grade structural zones to evaluate this promising style of mineralization.
SUMMARY OF INDICATED AND INFERRED RESOURCES AT NORTH BULLFROG
BY DEPOSIT
Au Ag
grade grade
Tonnes (g/t) (g/t) Con- Con-
Au greater greater greater tained tained
Pros- Oxide cut-off than than than ounces ounces
pect state Class (g/t) cut-off cut-off cut-off gold silver
Jolly Oxidized Indi- 0.2 10,090,000 0.29 0.49 94,000 159,000
Jane cated
May- Oxidized Indi- 0.2 5,140,000 0.54 0.34 88,577 56,187
flower cated
Total indicated 0.2 15,230,000 0.37 0.44 182,577 215,187
Conne- Oxidized Inf- 0.2 550,000 0.49 9,000
ction erred
Jolly Oxidized Inf- 0.2 15,900,000 0.25 0.38 129,000 194,000
Jane erred
May- Oxidized Inf- 0.2 3,090,000 0.46 0.26 46,096 25,532
flower erred
Sierra Oxidized Inf- 0.2 61,790,000 0.27 0.94 540,000 1,867,000
Blanca erred
Sierra Un- Inf- 0.2 74,300,000 0.29 0.89 686,000 2,126,000
Blanca oxidized erred
Total inferred 0.2 155,630,000 0.28 0.84 1,410,096 4,212,532
Resource estimate
The company retained Gary Giroux, MSc, PEng, of Giroux Consultants Ltd., to prepare an updated mineral resource estimate for the North Bullfrog project. The updated mineral resource estimate for each area of North Bullfrog is based on three-dimensional geologic models developed by Corvus geologists using geology logs from the drill holes along with alteration and geochemical data. The grade distributions for gold and silver were evaluated using lognormal cumulative frequency plots for samples within both the mineralized solid and the surrounding waste. Drill holes were compared with the mineralized solids and the points each hole entered and left the solids were recorded. Uniform down hole composites, plus-5.0/minus-2.5 metres in length, were formed and made to honour the solid boundaries. Pairwise relative semi-variograms were produced from composites within the mineralized solid for both gold and silver. For this resource estimate, the averages of the specific gravities for numerous samples were used to calculate the densities for the different geologic units in the models. A block model with blocks 10 m by 10 m by five m in dimension was superimposed over the mineralized solids. At Mayflower the model was rotated 45 degrees to better fit the solid but other areas were not rotated. Grades for gold and silver were interpolated into all blocks, with some percentage within the mineralized solid, by ordinary kriging.
Corvus will file the full NI 43-101 resource report on SEDAR by Nov. 11, 2011.
SUMMARY OF 72-HOUR CYANIDE BOTTLE ROLL RECOVERY
TESTS FOR NORTH BULLFROG PROJECT
Gold Four-hour Total
Test ID Target area (g/t) Oxidation recovery recovery
48436 B Sierra Blanca 0.51 Oxide 87% 94%
48436 C Sierra Blanca 0.45 Oxide 96% 93%
48434 B Sierra Blanca 0.29 Oxide 79% 90%
48433 C Sierra Blanca 0.47 Oxide 79% 77%
48433 A Sierra Blanca 0.71 Mostly oxide 79% 87%
48433 D Sierra Blanca 0.37 Mostly oxide 69% 70%
48434 D Sierra Blanca 0.35 Mixed ox/sulphide 68% 72%
48433 B Sierra Blanca 0.36 Mixed ox/sulphide 46% 47%
48436 A Sierra Blanca 0.35 Mixed ox/sulphide 42% 40%
3165-6 Mayflower 1.10 Oxide 61% 90%
3165-5 Mayflower 1.70 Oxide 60% 83%
3165-4 Mayflower 0.60 Oxide 76%
3165-7 Mayflower 2.40 Oxide 56% 71%
3165-8 Mayflower 11.10 Mostly oxide 41% 91%
3165-9 Mayflower 1.20 Mostly oxide 33% 68%
48432 B Jolly Jane 0.55 Oxide 94% 95%
48432 A Jolly Jane 0.46 Oxide 93% 90%
48432 C Jolly Jane 0.37 Oxide 85% 89%
48432 D Jolly Jane 0.32 Oxide 87% 85%
48456 B Connection 4.23 Oxide 78% 91%
48456 A Connection 5.87 Mixed ox/sulphide 32% 48%
The bottle roll tests were conducted on 75-micron material from oxidized and partially oxidized RC drill samples collected at various North Bullfrog prospects. The four-hour recovery indicates the percentage of gold that went into solution in the first four hours. The total recovery indicates the total amount of gold that was dissolved in 72 hours.
About the North Bullfrog project, Nevada
Corvus controls 100 per cent of its North Bullfrog project, which covers approximately 24 square kilometres in southern Nevada just north of the historic Bullfrog gold mine formerly operated by Barrick. The property package is made up of a number of private mineral leases of patented federal mining claims and 161 federal unpatented mining claims. The project has excellent infrastructure, being adjacent to a major highway and power corridor.
The project currently includes numerous prospective gold targets with four (Mayflower, Sierra Blanca, Jolly Jane and Connection) containing an NI 43-101-compliant estimated indicated resource of 15 million tonnes at an average grade of 0.37 gram per tonne gold for 182,000 ounces of gold and an inferred resource of 156 million tonnes at 0.28 g/t gold for 1.41 million ounces of gold (both at a 0.2 g/t cut-off), with appreciable silver credits. Mineralization occurs in two primary forms: (1) broad stratabound bulk-tonnage gold zones such as the Sierra Blanca and Jolly Jane systems; and (2) moderately thick zones of high-grade gold and silver mineralization hosted by structural zones with breccias and quartz-sulphide vein stockworks such as the Mayflower and Yellowjacket targets. The company is actively pursuing both types of mineralization.
A video of the North Bullfrog project showing location, infrastructure access and 2010 winter drilling is available on the company’s website.
Qualified person and quality control/quality assurance
Jeffrey A. Pontius (CPG 11044), a qualified person as defined by National Instrument 43-101, has supervised the preparation of the scientific and technical information (other than the resource estimate) that form the basis for this news release and has approved the disclosure herein. Mr. Pontius is not independent of Corvus, as he is the chief executive officer, and holds common shares and incentive stock options.
Gary Giroux, MSc, PEng (British Columbia), a consulting geological engineer employed by Giroux Consultants Ltd., has acted as the qualified person, as defined in NI 43-101, for Giroux’s mineral resource estimate. He has over 30 years of experience in all stages of mineral exploration, development and production. Mr. Giroux specializes in computer applications in ore reserve estimation, and has consulted both nationally and internationally in this field. He has authored many papers on geostatistics and ore reserve estimation, and has practised as a geological engineer since 1970 and provided geostatistical services to the industry since 1976. Both Mr. Giroux and Giroux Consultants Ltd. are independent of the company under NI 43-101.
The work program at North Bullfrog was designed and supervised by Russell Myers (CPG 11433), president of Corvus, and Mark Reischman, Corvus Nevada’s exploration manager, who are responsible for all aspects of the work, including the quality control/quality assurance program. On-site personnel at the project log and track all samples prior to sealing and shipping. All sample shipments are sealed and shipped to ALS Chemex in Reno, Nev., for preparation and then on to ALS Chemex in Reno, Nev., or Vancouver, B.C., for assaying. ALS Chemex’s quality system complies with the requirements for the International Standards ISO 9001:2000 and ISO 17025:1999. Analytical accuracy and precision are monitored by the analysis of reagent blanks, reference material and replicate samples. Quality control is further assured by the use of international and in-house standards. Finally, representative blind duplicate samples are forwarded to ALS Chemex and an ISO-compliant third party laboratory for additional quality control.
We seek Safe Harbor.
