The Briggs gold property ("Briggs") was acquired by the Company in 1990. Briggs was initially constructed in 1995; production ceased in 2004 due to gold-market conditions, and commercial production recommenced in mid-2009. Briggs is a conventional open-pit mine that uses heap-leach gold recovery. Targeted gold recovery is 80 percent. Briggs is located on the west side of the Panamint Range near Death Valley, California. No royalties are payable at Briggs. All of the mining claims are located on land administered by the Bureau of Land Management ("BLM").
The report details an estimate of mineral reserves and mineral resources, which are summarized in the tables below.
Briggs mineral reserve summary is based on a 0.0069 opt gold incremental leach cut-off grade calculated using $1,300 per ounce gold supported by the report titled “2012 NI 43-101 Technical Report on the Briggs Mine, Inyo County, California” dated May 29, 2012 with an effective date of March 26, 2012 (the “Briggs Report”) prepared by Alan C. Noble, P.E. of Ore Reserves Engineering, Michael J. Read, SME-RM of Chlumsky, Armbrust & Meyer LLC, William R. Stanley, SME-RM, V.P. Exploration of the Company, and Douglas E. Stewart, P.E., former V.P. and COO of the Company. Messrs. Noble and Read are independent qualified persons in accordance with NI 43-101 and Messrs. Stanley and Stewart are non-independent qualified persons in accordance with NI 43-101. The Briggs Report was filed on SEDAR on May 22, 2012. The mineral reserve has been updated and reconciled by Mr. Read for mine production through 2014 and is current as of December 31, 2014.
Mineral Resources include Proven and Probable Reserves.
Briggs Report, NI 43-101 Technical Report Briggs Mine, dated May 29, 2012; 0.006 opt gold cut-off, adjusted for actual production through December 31st, 2014 and other changes during production.
Cecil R Report, NI 43-101 Technical Report Cecil R Gold Property, March 2010; using a 0.010 opt gold cut-off.
Definitions used are consistent with those adopted by the Canadian Institute of Mining, Metallurgy and Petroleum ("CIM") Council in December 2005, as amended, and prescribed by the Canadian Securities Administrators' National Instrument 43-101 and Form 43-101F1, Standards of Disclosure for Mineral Projects. The measured and indicated resources stated above include reserves, which are a sub-set of resources. Mineral resources that are not mineral reserves do not have demonstrated economic viability. Inferred resources are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as mineral reserves.
In late 2008 and into 2009, Atna evaluated exploration targets that may extend the project's mine-life. One of the targets, the Briggs Main Deep ("BMD") zone has now been cut by 22 drill holes. With the completion of the second phase of drilling, mineralization has now been intersected in drill holes over a north-south distance of 1,000 feet and an east-west distance of 750 feet. Atna is currently modeling the BMD zone to estimate the tonnage and grade of the new mineralization. Thickness of the sub-horizontal mineralized zone varies significantly within the drilled area ranging from 25 feet in the southern most intercepts to over 250 feet in the northern portion of the zone. The BMD mineralization remains open to the east and north.The mineralization comes within 40 to 50 feet of the $750 ounce per gold design pit bottom. The BMD remains open for expansion to the north, south and east of the current intercepts.
Briggs History and Geology
The Briggs Mine is located in Inyo County, California about 50 miles east of the town of Ridgecrest, California. The Briggs property consists of 198 unpatented and two patented mining lode claims, and one patented and 18 unpatented millsite claims that together cover a total area of approximately 4,480 acres.
The information presented on this web page was prepared under the supervision and review of William Stanley, V.P. Exploration of Atna, a Registered Member of the Society for Mining, Metallurgy, and Exploration, a Licensed Geologist and Qualified Person, as defined in NI 43-101, and has verified the authenticity and validity of the technical information contained herein.
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