The Seven Devils Project is 55 miles south of Winnemucca, Nevada, and consists of fifty-four 100% Redstar-owned claims and sixteen leased claims. The project contains extensive volcanic-hosted, low-sulfidation epithermal gold mineralization, with surface values reaching 2.6 ppm (g/t) in preliminary sampling, as well as mineralization in underlying sedimentary rocks.
The gold system lies along a regional, north-trending structural zone which contains several important, low-sulfidation, volcanic-hosted gold deposits north of the project, including the Sleeper, Sandman and Goldbanks deposits. This structural zone, which Redstar terms the Western Nevada Rift, is parallel to and similar to the Northern Nevada Rift, which localizes a series of similar productive volcanic-hosted gold systems about 50 miles to the east, including the Mule Canyon, Fire Creek and Buckhorn gold deposits. All these gold systems represent a class of productive gold deposits in the Great Basin region containing both high-grade veins and low-grade disseminated mineralization of Middle Miocene age hosted in Middle Miocene volcanic rocks, the best example being the Midas district (Ken Snyder mine). Mineralized volcanic rocks at Seven Devils lie beneath basalt flows dated as Middle Miocene, and it is likely that the gold system is a member of this important class.
Previous exploration at Seven Devils focused on mineralization within a small window of Mesozoic carbonates beneath the Miocene volcanics. However, Redstar's work has shown that the overlying volcanics are extensively altered and mineralized and offer a stronger exploration target not well tested by previous exploration. Gold occurs in poorly-exposed pervasively-silicified volcanic conglomerate at the base of the volcanic section and in silicified ash-flow tuff. Rock-chip sampling by Redstar has returned gold to 2.6 ppm in the conglomerate, 1.44 ppm in the ash-flow tuff, and 896 ppb in discontinuous zones of silicified limestone. A basaltic breccia pipe cuts the carbonate section near the contact with the overlying volcanics and contains 0.636 ppm gold at surface. Nearby basalt dikes are also weakly mineralized and locally contain elevated selenium (Se) and strongly-elevated antimony (Sb) and arsenic (As); Se is a trace element characteristic of productive low-sulfidation gold deposits.
Historic exploration drilling in the late 1980's was shallow (average depth of 350 feet in 29 holes) and largely tested the basement. Although a number of mineralized intervals were encountered with gold values to 2.52 ppm, most assays were by atomic absorption (AA) without fire assay. The AA analysis may have underestimated grade where gold is associated with disseminated sulfides. Outcropping mineralization is locally accompanied by disseminated pyrite, and Redstar's outcrop samples adjacent to historic drill-hole collars have returned higher grades than those intersected in the holes. Thick intervals of anomalous gold were intersected in the volcanics; for example, one hole collared at an isolated knob of silicified tuff within a large alluvial basin, intersected 145 feet of anomalous gold from 125 to 270 feet, with a high of 1.125 ppm.
Gold mineralization is coincident with pervasive silicification, quartz veinlets, hydrothermal brecciation, widespread anomalies in As, Sb and Hg, and locally Se and Mo. The strongest correlation with Au is Mo, and this is also the case with the Sleeper deposit, which produced approximately 1.7 Moz of gold from bonanza-grade veins. Fluorite occurs locally with gold mineralization; fluorite is a common late-stage mineral in the high-grade veins at Midas. Gold mineralization occurs over a strike length of at least 6,200 feet, with strongly-anomalous trace elements covering 11,000 feet of strike. Structural controls to mineralization are not conspicuous, but evidence points to a north-northwest district-scale control.
Large areas likely to be underlain by silicified and mineralized volcanics remain untested by drilling, and proper fire assay analysis in areas previously drilled may increase grades. The gold system remains open in all directions. Mineralized volcanics are concealed by alluvium and post-mineralization volcanic rocks north and east of the window, and mineralization is open to the south through a large alluvial basin which may have been localized by mineralization-related structures. In addition to the known gold mineralization and the potential to expand it, the prospectivity of the Seven Devils project is enhanced by the probable Middle Miocene age for mineralization and similarities to the nearby Goldbanks deposit. Thus, the project has the potential for high-grade veins in addition to the known disseminated mineralization. Considering the project's location long the western Nevada rift trend and the evidence that the gold system is likely part of the Middle Miocene class, it is surprising that no exploration work has been conducted since 1990.
Redstar is completing additional sampling, mapping and data compilation and will begin seeking a partner to advance the project.
Click to enlarge
Limonite-stained, locally pyritic, silicified volcanic rocks.
Assays to: 2.61 ppm gold, 985 ppm arsenic, 3.4 ppm mercury and 59 ppm antimony