Neighbours World's Largest Primary Gold Mine
The Tonkin Project is a gold mining property located within the Battle Mountain-Eureka Trend in Eureka County, Nevada. Located just 8 miles south of Barrick Gold’s Cortez Mine (producing ~1.2 million ounces gold in 2011), this area continues to be one of the most prolific gold trends in the world. Recent discoveries by Barrick (Goldrush and Red Hill) have demonstrated that there remains excellent potential for new large discoveries with good grade.
Summary of April 2008 Resource Estimate
||Grams per tonne
|Measured + Indicated
From 1985 through 1989, Tonkin produced approximately 30,000 ounces of gold utilizing an oxide heap leach and a separate ball mill involving bioxidation to treat the problematic sulphide ore. Due to cost escalation and recovery issues associated with the refractory and preg-robbing carbonaceous mineralogy, the operation was forced to shutdown.
Current Test Work:
McEwen Mining has additional metallurgical test work underway to further evaluate conventional flotation and bioxidation possibilities at Tonkin. Recent test results indicated that approximately 50-55% of the gold would report to a concentrate. In order to increase this percentage SGS performed sub-microscopic test work in Q4 2013 to determine the reason for the low gold recoveries. The results indicate that sulphide mineralization may have been already oxidized prior to this test work starting since the samples used to perform the test were several years old. McEwen Mining is reviewing proposals that would include fresh mineralization that would require drilling three additional holes in order to rerun the flotation tests.
The Tonkin resource estimates on this page were derived from: (1) the report titled "Technical Report on Tonkin Project" with an effective date of May 16, 2008. The report was prepared by Alan C. Noble, P.E., Ore Reserves Engineering and Richard Gowans, Micon International, all considered independent of the Company as defined in Section 1.5 of NI 43-101. All other resources were prepared by Steven Brown, of US Gold Corporation. To access the report click here. And, (2) a news release titled “McEwen Mining Q3 2013 Results" released on November 8, 2013 by McEwen Mining Inc. To access the news release click here.
McEwen Mining reports its resource estimates in accordance with standards of the Canadian Institute of Mining, Metallurgy and Petroleum referred to in Canadian National Instrument 43-101 ("NI 43-101"). These standards are different from the standards generally permitted in reports filed with the SEC. Under NI 43-101, McEwen Mining reports measured, indicated and inferred resources, measurements which are generally not permitted in filings made with the SEC. According to Canadian NI 43-101 criteria, the estimation of measured resources and indicated resources involve greater uncertainty as to their economic feasibility than the estimation of proven and probable reserves. Under SEC Industry Guide 7 criteria, measured, indicated and inferred resources are considered Mineralized Material. The SEC considers that in addition to greater uncertainty as to the economic feasibility of Mineralized Material compared to proven and probable reserves, there is also greater uncertainty as to the existence of Mineralized Material. U.S. investors are cautioned not to assume that measured or indicated resources will be converted into economically mineable reserves. The estimation of inferred resources involves far greater uncertainty as to their existence and economic viability than the estimation of other categories of resources.
Mineral resources which are not mineral reserves do not have demonstrated economic viability.