Metal Bank has completed an initial drilling programme on the Bluestone Prospect, Mason Valley copper project within the Yerington Copper District, Nevada, US.
Drill testing of outcropping copper targets to the south-east of the Bluestone pit returned 9m @ 0.76% Cu from 22m. Best drill results to date are from the breccia at the western end of the Bluestone pit returning 42m @ 1.51% Cu reported on 30 July 2015.
New geological mapping combined with first phase drilling results indicate the high grade plunging breccia target dips to the north-east – testing scheduled for next drilling phase
MBK chairman Inés Scotland said: "Our initial drill programme at Bluestone intersected broad zones of copper mineralisation. Combined with new geological modelling and detailed mapping, this suggests a breccia hosted copper system that plunges to the north-east. Such a target model has not previously been tested and may very well represent a significant resource opportunity."
Results for the remaining six reverse circulation drill holes of the eight holes that were completed as part of an initial Bluestone programme1 have returned further copper mineralized zones associated with a hydrothermal breccia. Further drilling is planned to commence in the coming month, subject to rig availability, to target the interpreted north-east extensions of the broad copper mineralised zones.
The Bluestone prospect is centered on the Bluestone copper mine which produced approximately 1.5Mt @ 2.5% Cu. Copper mineralisation is hosted within a skarn altered breccia pipe which was likely emplaced as part of a vertical body but has now been structurally tilted onto its side as a shallow plunging copper ore system.
Geological modelling based on additional detailed geological mapping and results from this initial drill programme indicate breccia pipe plunges to the northeast rather that to the south or south-east which was partly tested during this initial drilling programme. Refer to Figure 2 showing geological plan and drill hole locations and refer to Figure 1 showing an interpreted long section based on the new geological modelling and interpretation.
About the Mason Valley Copper Project
The Yerington camp is a significant copper district with world class statistics supported by a resource base of over 12Mt of copper3 and past production of approximately 1Mt of copper. Mineralisation within the Yerington copper district is intimately associated with the Yerington batholith creating large scale porphyry style deposits together with associated high grade skarn and breccia style deposits.
The Mason Valley Copper Project consists of numerous historical underground mines to depths of up to 150m. Approximately 3.8Mt at a grade of 2.5% to 6.2% copper from 1910 to 1931 was collectively produced for three of these mines for which historical documentation is currently available. These are:
- Mason Valley Mine historical production 1.7Mt @ 2.5% to 6% Cu
- Bluestone Mine historical production 1.5Mt @ 2.5% to 3.5% Cu
- Malachite Mine historical production 0.6Mt @ 3.5% to 6.2% Cu
The closure of these mines coincided with the onset of the ‘Great Depression’. Past exploration and drilling over the Mason Valley mining camp has been limited due to the previous fragmented ownership of the mining claims/tenure. Under the current JV Agreement the entire Mason Valley mining camp covering four historical copper mines has been secured under 10km2 of contiguous claims.