ON-TREND, DRILL-READY NEVADAN GOLD ASSET WITH AN UPDATED AND INCREASED 2021 RESOURCE ESTIMATE
- Proven gold mineralization comprising 21.8Mt @ 0.7g/t gold for 494,000 oz Au (see section on Mineral Resource estimate):
- Indicated Resource of 18,550 kt @ 0.73 g/t gold for 433k ounces Au
- Inferred Resource of 3,246 kt @ 0.58 g/t gold for 61k ounces Au
- Updated 2021 Sandman NI43-101 resource estimate increased by 60% since the 2007 resource estimate
- Located on renowned gold trend in #1 Mining Jurisdiction in the World (~23km from Sleeper Mine that produced 1.7M oz Au @ 7 g/t average head grade, 1986-1996).
- Extensive & consolidated land package (117km2 Sale Boundary) with numerous high grade gold exploration targets identified from historical data
- Expansion potential with significant drilling and exploration conducted post-resource estimate & massive gaps in exploration under cover
- Permits In-Hand from BLM and NDEP across land package in mining friendly jurisdiction with no known environmental sensitives
- Drill program planned to commence in Q1 2021 - already permitted for drilling
Sandman is located in Townships 36 and 37 North, Ranges 35 and 36 East, Mount Diablo Meridian, Humboldt County, Nevada, USA. The property is situated south of the Slumbering Hills and west of the Tenmile Hills, circa 24 km northwest of the town of Winnemucca, Nevada. The property lies 23 km south of the successful Sleeper gold mine1 which historically produced 1.7M oz Au with M&I Resources in excess of ~3M oz Au2 (Figure 1). Sandman is accessed by driving west from the town of Winnemucca on Jungo Road for 15 km, and then an additional eight km to the north on dirt roads that lie largely within the property boundaries.
Significant gold mineralization at Sandman has been identified at Southeast Pediment, Silica Ridge, North Hill, and Abel Knoll deposits (Figures 2 and 3), for which an updated 2021 NI43-101 mineral resources estimate has been completed (see section on Mineral Resource Estimate).
No significant historic mining activities have taken place within the Sandman project limits. Modern exploration of the Sandman project began in 1987 when Kennecott Exploration Company (“Kennecott”) discovered gold in outcrop at North Hill. Kennecott and Santa Fe Pacific Gold Corporation (“Santa Fe”) formed a joint venture and conducted geologic mapping, surface sampling, geophysical surveying, trenching, drilling, and metallurgical testing through 1994. The joint venture drilled 275 reverse-circulation (“RC”) holes and three diamond-drill core (“core”) holes in this period, as well as 4,000 shallow auger holes to sample bedrock beneath the extensive sand cover. A block of claims staked by U.S. Borax was acquired by the joint venture in 1989. U.S. Borax had drilled 37 RC holes within these claims. The work of these companies led to the discoveries and partial definitions of the Southeast Pediment, Silica Ridge, and North Hill gold deposits, as well as the identification of the Adularia Hill, Basalt Hills, Basalt Fields, and Abel Flat exploration target areas (Figure 3).
Kennecott and Santa Fe terminated their joint venture and conveyed their individual holdings at Sandman to Western States Mining (“WSMC”) in 1997. WSMC and NewWest Gold Corporation subsequently conducted extensive exploration of the property, including rock chip and soil sampling, geophysical surveying, trenching, drilling, and metallurgical testing. WSMC also excavated a test pit at Southeast Pediment measuring roughly 60m long by 15m wide by 5m deep. A 1,067-ton bulk sample of relatively high-grade mineralization was mined and shipped to the Twin Creeks mine of Newmont for milling and leaching.
In 2005 NewWest acquired the property from WSMC and employed Mine Development Associates to prepare a 43-101 report. In 2007 Fronteer acquired the Sandman property from NewWest Gold and then in 2008, formed a joint venture with Newmont. In 2011, Newmont acquired Fronteer and initiated Stage 2 studies and reporting, including drilling 364 holes within the Sandman AOI. In addition, Newmont began Stage 3 initial permitting, including waste characterization, aquifer testing, water rights acquisition, and metallurgical studies. The project was put largely on hold by Newmont between 2012 and 2016 due primarily to low gold prices.
The property boasts an extensive geological, geochemical and geophysical database with significant drilling and geological advancement post the 2007 resource estimate. The historical databases, in addition to 974 drill holes, includes 4,293 soil samples from 6 surveys, 3,519 rock chip samples from 23 surveys and an abundance of geophysical datasets including one airborne EM survey, three airborne magnetic surveys, one airborne radiometric survey, two CSMAT surveys at Silica Ridge and Southeast Pediment (2011, 2012), one IPRES survey, 576 gravity stations from one survey, and a basin model1.
Post the 2007 resource estimate, significant additional permitting, exploration and infill drilling has been conducted that has not been incorporated in an updated 43-101 Resource Estimate. Gold Bull has commissioned and commenced an updated NI43-101 resource estimate, which is expected to be announced in early 2021.
1 Newmont Management Presentation, March 2019
GEOLOGY & MINERALIZATION
Sandman lies along the north-northwest-trending eastern margin of the Sleeper or Kings River Rift, which is regionally part of the Western Northern Nevada Rift (NNR). The Sleeper Rift consists of a regional aeromagnetic and gravity linear high that extends from the Idaho border to the Sleeper gold mine, (located 23 km N-NW of Sandman; Figure 1), through Sandman, and through the Goldbanks gold deposit (located 48 km S-SE of Sandman). Much of the property area is covered by windblown sand deposits and Late Tertiary to Quaternary basalt. Mapping, exploration drilling, and extensive shallow auger drilling through the sand indicate that most of the sand and basalt in the project area are underlain by a section of Tertiary tuffaceous rocks and andesite, which in turn overlie Late Triassic to early Jurassic metasedimentary clastic and subordinate carbonate rocks.
The Southeast Pediment, Silica Ridge, North Hill, and Abel Knoll Au+Ag mineralization at Sandman are classified as low-sulfidation, quartz-adularia, epithermal deposits. The mineralization is hosted by Tertiary volcanic rocks, primarily in tuffaceous units, andesite porphyry, tuffaceous sedimentary units, and basalt. Northwestern Nevada contains a number of similar middle Miocene Au-Ag deposits that occur in silicic volcanic or subvolcanic rocks, including the Sleeper, Tenmile, National, and Hog Ranch deposits (Conrad et al., 1993). The abundance of adularia and relative paucity of silicification associated with much of the Sandman mineralization compares more closely to the mineralization type at the Round Mountain mine located to the south in Nye County, Nevada.
In general, higher-grade gold mineralization at Sandman can be stratigraphically controlled along contacts between basalt flows, interbedded fluvial conglomerates and tuffaceous rocks (e.g., North Hill Deposit), or structurally controlled as lens-shaped pods, with high-continuity, lower-grade disseminated gold in sediments and volcanics (e.g., Silica Ridge and SE Pediments Deposits). Quartz-adularia alteration dominates the ore zones, whereas propylitic, argillic, and sericitic alteration are associated with the known resource areas more distally.
Silica Ridge Target
The primary host units at Silica Ridge are fluvial siltstone, sandstone, conglomerate, and epiclastic tuff. Mineralization is primarily focused along the main NNE and NW fault sets (Figure 4) over a known strike length of 850 meters. Gold values are elevated in fault breccias, especially where coincident with conglomerate beds. The mineralization at Silica Ridge occurs over a 700 by 250m area. Previous drilling at Silica Ridge has intersected high grade oxide gold mineralisation including:
|Drill Hole No||From-m||To-m||g/t
SE Pediment Target
Southeast Pediment is an outcropping, moderately dipping, high-grade vein system hosting a predominantly oxide gold resource at the intersection of two prominent structures (Figure 5). Approximate dimensions Southeast Pediment are 305 meters in length by 30 to 60 meters in width. Drilling has intersected a wide zone of high-grade sulfide mineralization (hole NSM-051) below the oxide gold vein, illustrating the high-grade nature and strong continuity of mineralisation at SE Pediment, and suggesting the presence of multiple mineralised vein structures in the deposit. Highlights from historic drilling at SE Pediment include:
|Drill Hole No||From-m||To-m||g/t Au||g/t Ag||interval|
North Hill Target
The North Hill target has been characterized as an oxidized, low-sulfidation, epithermal gold occurrence that extends 550m long, 430m wide. Mineralization at North Hill is controlled by a combination of low-angle contacts between the various basalt flows and the interbedded fluvial conglomerates and tuffaceous rocks (Figure 6). Previous drilling intersected oxide gold mineralization stating at a depth of less than 25m and high-grade intercepts at North Hill include:
|Drill Hole No||From-m||To-m||g/t Au||interval|
2021 43-101 MINERAL RESOURCE ESTIMATE
An updated 2021 mineral resource report for the Sandman project was modeled and estimated in accordance with Canadian Institute of Mining, Metallurgy, and Petroleum (“CIM”) definitions. Gold resources as Southeast Pediment, Silica Ridge, North Hill, and Abel Knoll are summarized in Table 1.
Table 1. Sandman Updated Gold Resource Estimate
An Indicated Resource of 433,000 oz Au plus an Inferred Resource of 60,800 oz Au result in a total Resource of 494,000 oz Au at Sandman from four of the known five deposits. Metallurgical information completed to date from Sandman indicates that different processing methods and operating costs will be required for the oxidized rock compared with the unoxidized rock, or fresh rock. A cut-off grade of 0.15 g/t gold has been applied to the oxide rock which compares with the cut-off grade for unoxidized (fresh) rock of 0.30 g/t gold.
MINERAL PROCESSESING & METALLURGICAL TESTING
Bottle roll, column leach, and some gravity concentration tests have been undertaken on trench and drill- hole samples from the Southeast Pediment, Silica Ridge, and North Hill deposits. The bottle roll and column data indicate that the gold mineralization tested is amenable to direct cyanidation. The data consistently show that cyanide extractions increase with decreasing particle size for the samples tested. Samples that were pulverized to -100 mesh yielded an average gold extraction of 94.3%, while RC chip samples tested at the ‘as-received’ size and samples crushed to 6.35mm yielded an average gold extraction of 77.8%. There is no clear relationship between the cyanide extractions and gold grades of the head samples, although there is some evidence that samples with higher head grades require a longer leach time to achieve comparable extractions. Cyanide consumptions and lime requirements are low to moderate.
The bulk sample extracted from the test pit at Southeast Pediment was sent to Newmont’s Twin Creeks mine for milling and cyanide leaching. Over 95% of the gold in the 1,067-ton sample was recovered, which is consistent with the bottle roll results generated from samples pulverized to -100 mesh.
Exploration work completed at Sandman to date has resulted in the discovery of four gold deposits and the identification of other target areas that remain to be explored. Sandman provides the potential for near-term production from one or more of the known deposits. There is also excellent potential for the discovery of new precious-metal mineralization beyond the limits of the deposits, as demonstrated by the discovery of the Abel Knoll deposit in 2006.
Gold Bull believes that Sandman is a property of merit that warrants significant additional expenditures. Programs aimed at increasing the size of the Sandman mineral resources and defining new areas of mineralization are justified in a Phase I work program. Drilling at the four deposit areas in 2006 and 2007 concluded with open-ended mineralization in a number of drill holes, and step-out RC drilling in these areas should continue.
Sandman is a large property that is extensively covered by alluvial gravels and wind-blown sand. Four discrete gold deposits have been discovered at Sandman, which proves the existence of multiple hydrothermal systems and suggests that the potential for the discovery of additional deposits is excellent. Geophysical, geochemical, and geological data have led to the identification of a number of quality exploration targets that are not fully explored. The Phase I program recommends first-pass or follow-up drill testing of these targets. Further work aimed at developing new exploration targets is also warranted. Geophysical and geochemical surveys should be completed with the goal of defining new targets. Additionally, scoping-level economic studies should be completed as deposit resources continue to be refined.
The Company’s Geology and Geophysics team has identified 42 drill hole targets for approximately 8000 m. The Company will commence with a Phase I drill program consisting of 3000 m for 17 drill holes in Q1, 2021.
Cherie Leeden, B.Sc (Applied Geology, Honours), MAIG, a “Qualified Person” as defined by National Instrument 43-101, has read and approved all technical and scientific information contained on this page. Ms. Leeden is the Company’s Chief Executive Officer.
The 2021 Mineral Resource Estimate (MRE) for the Sandman Project was completed by Steven Olsen, who is an Independent Consultant and is a qualified person under NI 43-101.