The SW Pipe project lies within the Cortez Gold Belt of north-central Nevada and consists of unpatented mining claims staked by NV Gold Corporation that cover approximately 6.5 square km (2.5 square miles). The project contains a sediment-hosted (Carlin-type) gold system 6 km southwest of the Pipeline gold mine. Pipeline, operated by Barrick Gold Corp., contains approximately 21 million ounces of gold (past production plus reserves). Historic vertical drilling at SW Pipe, mostly between 1989 and 1997 and within 150 m of surface, intersected significant shallow gold mineralization, including: 0.44 g/t over 17 m containing 2.36 g/t over 1.5 m, 0.75 g/t over 11 m containing 1.83 g/t over 3 m, and 0.60 g/t over 18 m containing 1.35 g/t over 5 m as outlined in Table 1. First-phase rock-chip sampling by NV Gold has returned gold values to 1.74 ppm with high arsenic and antimony, elements enriched in productive Carlin-type gold deposits. Mineralization is largely within 100 m of surface, and is hosted by siltstones and quartzite within the western-facies sequence (the upper-plate of the regional Roberts Mountains thrust fault). Gold is known over a vertical range of at least 300 m within an area of at least 1,300 by 500 m. Preliminary results indicate that north-northwest-striking faults may have localized mineralization which also spread laterally away from these "feeder" faults in a stratiform style along a major geologic contact, possibly a thrust fault. The north-northwest striking faults have not been tested by drilling, and faults of this orientation are the key control to localizing gold mineralization along the Cortez gold belt, including the nearby Pipeline, Cortez Hill and Goldrush deposits, which contain at least 40 million ounces of gold.
The Company has obtained and is continuing to review the historic exploration data, which includes original assay certificates and drill logs from drill holes, surface rock-chip and soil data, internal third party reports and geologic and geophysical interpretations. Although the historic exploration data was generated by reputable companies, NV Gold cannot verify the data or determine the quality assurance and quality control measures applied. Continuing work by NV Gold will be aimed at assessing the potential for mineralization beyond the historic drilling and, in particular, for mineralization within steep "feeder" structures which have not been tested by the historic drilling.
Selected Drill Hole Gold Composites*
|Hole||From (m)||To (m)||Length (m)||From (ft)||To (ft)||Length (ft)||Au g/t|
* Composites calculated at a cutoff of 0.1 g/t gold; mineralized thicknesses do not necessarily equate to true width.
System type: Volcanic-hosted, low-sulfidation epithermal gold
Target: High-grade veins and disseminated mineralization
The Seven Devils Project is 55 miles south of Winnemucca, Nevada, and 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 and locally older volcanic rocks and pre-Cenozoic basement, the best example being the Midas district. 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.
An area of gently-folded medium-bedded limestone of probable Mesozoic age occurs as a window through volcanic rocks in the central part of the project. The volcanics consists of basal volcanic conglomerate and sandstone, which are apparently laterally discontinuous, and a more extensive section of felsic ash-flow tuff, which also locally lies on the baesment carbonates. Basaltic breccia is common along the unconformity between the basement and the overlying volcanics and is interpreted as intrusive, forming sills and dikes. Mineralization occurs in all these units, which are overlain by an uppermost section of unaltered and umineralized basalt flows that has been dated at about 16 Ma.
Minor areas of silicification (jasperoid) occur in the limestone; the matrix of the volcanic conglomerate as well as clasts are ubiquitously silicified and pyritic; the felsic tuff is locally pervasively silicified and cut by chalcedonic crackle veinlets; and the intrusive basalt is largely argillically altered. Rock-chip sampling has returned gold to 2.65 ppm in the conglomerate, 1.44 ppm in the ash-flow tuff, 435 ppb in silicified sandstone, 636 ppb in argillized basalt and 896 ppb in silicified limestone. The low-sulfidation style gold mineralization is coincident with pervasive chalcedonic silicification, quartz veinlets, hydrothermal brecciation and widespread anomalies in As, Sb and Hg; Ag values are low. Selenium is locally anomalous in altered and mineralized basalt; Se is a trace element characteristic of productive low-sulfidation gold deposits. After Ag, the strongest correlation with gold is Mo, which reaches 411 ppm; this is similar to the high-grade Sleeper deposit. Fluorite is common with gold, both in the basement and volcanics; fluorite occurs 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. At the district scale, mineralization is concentrated near the base of the volcanic section.
Previous exploration at Seven Devils from 1988-1990 consisted of 29 shallow drillholes (average depth of 350). The program focused on sediment-hosted mineralization in the basement window. The significance of the volcanic-hosted mineralization wasn't recognized until the end of the exploration program (final 4 holes), and such mineralization remains poorly explored. Although a number of mineralized intervals were encountered in the drilling, 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.
The gold system remains open in all directions, with large areas likely to be underlain by silicified and mineralized volcanics beyond the pre-Tertiary window untested by drilling. Mineralized volcanics are concealed by alluvium and post-mineralization basalt north and east of the window, mineralization is open to the south through a large alluvial basin, and mineralization is open to the west within the lower part of the felsic tuff. In addition to the known gold mineralization and the potential to expand it, the prospectivity of the project is enhanced by the probable Middle Miocene age for mineralization, geologic similarities to the nearby Goldbanks deposit, the location long the western Nevada rift trend and the elevated Se and Mo with gold. By comparison with other Middle Miocene low-sulfidation systems, the project has potential for high-grade veins in addition to the known disseminated mineralization.
It is recommended that the next exploration phase consist of additional detailed mapping to further evaluate the volcanic stratigraphy and structure. Additional rock-chip and possibly soil sampling is warranted to identify and delineate gold and trace-element anomalies. Third, geophysics, such as CSAMT, should be considered across the alluvial basin in an attempt to identify silicified zones and structures.
Long section through the project showing known and projected geologic units and the known and potential distribution of mineralization.
Cross section through the project showing known and projected geologic units and the known and potential distribution of mineralization
System type: Rochester-type Ag-Au system
Target: Disseminated Ag-Au mineralization
The Root Spring Project is 80 km south of the city of Winnemucca and 26 km east of the world-class open-pit Rochester silver mine operated by Coeur Mining. The project contains an epithermal/mesothermal gold-silver vein stockwork system exposed at the edge of a large alluvial-covered valley. Mineralization is hosted in the Triassic Koipato volcanics, which were not previously identified in the area and consist of interbedded felsic and mafic volcanics. The Koipato hosts the Rochester Ag-Au deposit as well as the Spring Valley gold deposit 27 km northwest of Root Spring.
The project contains gently-dipping quartz veins and quartz-vein stockwork zones exposed for at least 1.2 km along a northwest strike, with individual veins to 5m thick. Extensions of the veins along strike as well as surrounding country rock are concealed by alluvial cover within a northwest-trending alluvial-filled valley corridor along a range front. Like the Rochester deposit to the northwest, the Root Spring Au-Ag system is adjacent to a Triassic granitic pluton. Surface rock-chip gold values in veins reach 9.36 ppm gold (0.273 ounces per ton, opt) accompanied by high silver reaching 1500 ppm (44 opt). The veins are surrounded by widespread, locally mineralized quartz-sericite-pyrite alteration of the host felsic volcanic sequence that is known principally from shallow drilling.
A limited first-phase drilling program in 2012 intersected Ag-Au mineralization down-dip of exposed veins; however, drilling was very shallow (68m average length). Results included 12.1m grading 14.02 g/t Ag and 0.16 g/t Au, 10.7 m grading 17.23 g/t Ag and 0.14 g/t Au and 9.4m grading 16.47 g/t Ag and 0.53 g/t Au. Importantly, the drilling confirmed the Koipato host section containing local disseminated tourmaline and fluorite and also intersected encouraging disseminated gold within felsite far from the exposed veins. Although the first-phase drilling failed to intersect potentially economic grades/widths of Ag-Au mineralization, the similarity of the host Koipato volcanics to nearby Rochester – Spring Valley, the range-front setting, the adjacent Triassic pluton, the extensive alluvial cover, the widespread silicification and sericitic alteration, and both disseminated and vein-style mineralization intersected in the drilling are prospective elements for further exploration.
Location of the Root Spring Project in northwestern Nevada
Veining exposed at Root Spring
System type: Sediment-hosted Carlin-type gold along Carlin Trend
Target: Replacement-style disseminated gold
The Richmond Summit Project is within the central Carlin Trend 4 miles northwest of the Mike copper-gold deposit within the Gold Quarry (Maggie Creek) district and 5 miles south of the Carlin gold mine, both areas operated by Newmont Mining Corporation. Gold production and reserves/resources in the Maggie Creek district total at least 29 million ounces, with at least 10 million ounces in the Carlin mine area.
The property lies at the southern tip of the Lynn window, an area exposing carbonate (calcareous) rocks in the lower plate of the regional Roberts Mountains thrust fault. Lower-plate carbonates host most of the gold mineralization along the Carlin trend, although mineralization locally extends into the overlying upper-plate rocks. Although rocks exposed on the project are dominantly upper-plate siliciclastics, thick sections of carbonates believed to part of the lower plate have been intersected in drilling and are locally exposed as thrust slices within the upper-plate rocks. In addition to this favorable stratigraphic setting, the project lies on the southern extension of the Post fault, which crosses the northeastern portion of the project. The northerly-trending Post fault system is a major structural control to world-class gold deposits in the northern Carlin trend north of the project such as Post-Betze (Goldstrike) and Meikle. The project contains numerous north trending, Late Eocene rhyolite and andesite dikes which follow the Post fault trend. These dikes can be traced north along the Post fault system from the project through the Genesis, Deep Post, Goldstrike and Meikle gold deposits. Carlin-trend gold mineralization occurred during emplacement of these dikes, which are common within the gold deposits. At Richmond Summit, known gold mineralization occurs along the margins of these dikes and within adjacent wallrock.
Carlin-type gold mineralization on the project occurs in several widely-spaced areas within upper-plate siltstones and greenstone along the margins of dikes. The strongest gold mineralization identified to date occurs in the Main Zone, where select surface samples reach 7.75 ppm Au. The mineralization is poorly exposed, but historic sampling in trenches returned 3.048 ppm gold over 20 feet, 4.960 ppm over 10 feet and 3.59 ppm over ten feet. Limited historic drilling (prior to 1991) intersected shallow gold mineralization within 200 feet of surface, including 2.540 ppm over 10 feet. Mineralization is hosted in greenstone and shale adjacent to and locally within a north-trending andesite dike and is accompanied by strongly-elevated arsenic (to 2.7%), antimony (to 450 ppm) and mercury (to 3.3 ppm), a signature consistent with Carlin-type gold mineralization. Other mineralized areas include the Ridge Zone, 1,200 feet west of the Main Zone, which contains anomalous gold at surface to 1.97 ppm in siliciclastic rocks and greenstone adjacent to a rhyolite dike; a float sample from Ridge returned 3.7 ppm.
Two deep core holes have been completed in the Main Zone and one at the Ridge Zone. One of the Main-Zone holes intersected anomalous gold to 400 ppb with strongly-anomalous As to 2,600 ppm along the sulfidized and argillized to silicified margins of a dike and within adjacent shales. The dike occupies a newly-recognized north-trending fault, which is apparently a significant control to the Main Zone mineralization. A second, deeper follow-up hole was unmineralized but successfully intersected lower-plate carbonates (based on conodont ages). Unfortunately, the hole largely followed the dike to depth without testing enough of the surrounding country rock. One deep core hole at the Ridge Zone also intersected lower-plate carbonates. Although unmineralized, the hole is believed to have failed to test the structure controlling the gold at surface. Therefore, drilling to date has not successfully intersected the roots of the two anomalies within the lower plate.
The target at Richmond Summit is structurally-focused gold mineralization with surrounding replacement-style mineralization similar to that in other gold deposits along the Carlin Trend. The exploration history at the Ren deposit near the Meikle mine on the northern Carlin Trend is a good example of the importance of persistence is locating lower-plate gold mineralization beneath mineralization in overlying upper-plate rocks. Ren, with a high-grade resource of approximately 2 Moz gold, was discovered on the 24th drill hole.
Location of the Richmond Summit Project along the Carlin Trend in northeastern Nevada.
System type: Volcanic-hosted, Low-sulfidation Epithermal Au-Ag
Target: Stockwork vein and disseminated gold
The Queens project is 8 miles southeast of the world-class Round Mountain gold mine (>13 Moz production and reserves; Kinross Gold Corp, Barrick Gold Corp) and 5 miles northeast of the Manhattan gold district. Like Round Mountain, Queens contains a disseminated gold system hosted in caldera-related volcanic rocks (ash-flow tuff). Preliminary sampling by Redstar has returned outcrop gold values to 0.587 ppm. Historic surface sampling during the early 1990’s returned values to 1.95 ppm gold in outcrop and 6.98 ppm gold in soil sampling. Shallow (200 to 500 feet) reverse-circulation drilling of sixteen holes in the early 1990’s returned significant gold intersections (Table 1). Hole 91-2 yielded 0.023 opt Au (0.793 ppm) over 75 feet (220-295 ft), including 0.034 opt (1.18 ppm) over 30 feet. Hole 91-5 returned 0.013 opt (0.462 ppm) over 55 feet (105-160 ft) and 0.015 opt (0.530 ppm) over 45 (220-265 ft). Local higher grades are present, reaching 0.198 opt (6.8 ppm) over five feet. Mineralization is known over a strike length of at least 1,500 feet and a plan width of up to 400 feet. Queens lies within a volcanic sequence which is part of the 25 million year-old (Ma) Manhattan caldera, part of a complex of calderas which erupted between about 24 and 26 Ma and includes the caldera hosting the Round Mountain deposit.
Table 1. Queens Historic Drillhole Assays*
|Hole||Length ft||ppb Au||Opt Au||From ft||To ft|
* Composites calculated at 250 ppb gold cutoff (0.25 g/t) and no more than 5 feet of internal waste.
Location of the Queens Project showing productive gold deposits in black
System type: Volcanic-hosted, low-sulfidation epithermal gold
Target: High-grade veins and disseminated mineralization
The Painted Hills project is in northwestern Nevada, in Humboldt County, 17 miles southwest of the town of Denio. The project exposes the upper parts of a low-sulfidation, volcanic-hosted epithermal gold system of probable Middle Miocene age and lies along the regional northeast-trending Black Rock Structural Boundary (BRSB), at its intersection with a northwest-trending fault zone. The BRSB localizes the productive Hog Ranch deposits and the Mountain View gold system southwest of Painted Hills. These deposits are members of a productive class of gold-silver deposits that formed during the Middle Miocene (~15 Ma) in the northwestern Great Basin and commonly contain high-grade veins in addition to disseminated mineralization. Notable examples include the Sleeper, Midas (Ken Snyder), Fire Creek, Mule Canyon, Rawhide, Goldbanks, Hollister and Hog Ranch deposits. Like Painted Hills, most of these deposits lie along regional fault zones like the BRSB.
Host rocks at Painted Hills consist of a gently-dipping sequence of basalt flows (known only from drilling) and successively overlying felsic tuffs/volcaniclastics and volcaniclastic sandstone. These units underlie the Middle Miocene (~15 Ma) Cañon rhyolite exposed on the west side of the mineralized area. A silicified felsic pyroclastic vent (intrusive exogenous dome) in the southwest part of the project area has been dated at 14 Ma.
The felsic tuffs and volcaniclastics are extensively argillized and contain anomalous As, Hg and Sb but no Au or Mo. The overlying sandstone is notably unaltered but locally contains stratiform opal and a 100 m-wide stockwork of north-trending opal veins. The opal is weakly anomalous in As, Sb and Hg. A northerly-trending silicified fault is exposed 500 m south of and on strike with the opal stockwork but is 55 m below the elevation of the exposed opal veins. Silicification along this fault is distinctly chalcedonic and contains strongly elevated As, Hg and Sb. The silicified pyroclastic vent also contains elevated As, Sb and Hg. The silicification and argillic alteration occur along a 1.6 km north-northeast trend that is inboard of and parallel to the range-front fault, which is several hundred meters to the east.
The only indication of gold prior to drilling was rare float of chalcedonic, pyritic silicified tuff from below the opal vein stockwork excavated by small-scale mercury mining in the 1970's; gold reaches 107 ppb with strongly-anomalous Hg, As, Sb and Mo. The opal veins and stratiform opal replacements, the argillic alteration and elevated Hg indicate that exposures represent the upper portions of an epithermal system. The discovery of at least anomalous gold prompted the first exploration drilling in 2007. The exploration model envisioned increasing gold at depth below the opal zone coincident with increasing crystallinity of silica and proximity to a deeper boiling level, where high-grade Au-Ag mineralization would be expected. The change with depth from opal to chalcedony containing anomalous gold supported this model, which has been proven in several districts in Nevada (e.g., Goldbanks and Hollister), where gold has been discovered beneath barren or Hg-bearing opal.
Four core holes totaling 1,852m (6076.5 ft) were angled to cross beneath the exposed vein and alteration trend; about 440m of strike was tested. All holes intersected multiple zones of silicification typically 25-40m thick with local stockworks of sulfidic chalcedony veins. The silicification occurs across a width of at least 200m. Gold values increase within 100m below surface within silicified and veined intervals, although gold reaches only 330 ppb over 0.75m. Gold correlates strongly with molybdenum, which reaches 1560 ppm Mo over 0.6m. Fine-grained blebs of molybdenum sulfide, interpreted as jordisite, occur within black, pyritic chalcedony veinlets. Gold is concentrated in these veinlets, with one "high-graded" separate yielding 1.5 ppm Au and 1.65% Mo. Mercury and Sb are enriched in shallower silicified zones, with Mo-As-Au enriched deeper. The strong correlation of gold with molybdenum is encouraging, as this also occurs at the Middle Miocene, bonanza-grade Sleeper vein deposit 85 km to the southeast.
The presence of vein sediment and the absence of bladed calcite/quartz, sugary quartz and adularia indicate that the potential gold-silver rich boiling level remains deeper or lateral to the small area drilled to date. Additional drilling is recommended to explore other portions of the mineralized trend, the range front and pediment to the east, and follow-up in the area drilled in 2007. The Sleeper deposit lies along a major range-front fault zone under alluvial cover, a similar setting to Painted Hills.
Location of Painted Hills Project in northwestern Nevada with Middle Miocene, low-sulfidation gold-silver deposits (red squares) and other gold deposits (white dots).
Examples of silicification in drill core with Au and trace-elements as noted for assay intervals typically 1.5m in length.
Examples of veining with silicification in drill core with Au and trace-elements as noted for assay intervals typically 1.5m in length.
Black, sooty, molybdenum-bearing sulfidic veinlets in deeper parts of drill holes; the strong correlation between Mo and Au at Painted Hills is similar to the nearby bonanza-grade Sleeper deposit.