Lewis Gold Property, Nevada
LOCATION: Approximately 2,225 hectares (5,500 acres) in Lander County, Nevada, within the Battle Mountain Trend, which hosts a series of gold mines (Marigold, Lone Tree, Fortitude, Phoenix, Twin Creeks, Midas, Trenton Canyon) with resources or past production collectively exceeding more than 25 million ounces of gold.
OPPORTUNITY: Precious Metals. The main exploration targets are high-grade, structurally controlled veins/faults and lower-grade, disseminated skarns and replacements associated with northerly-trending structures and Tertiary intrusions.
Nevada is the world's third largest gold-producing region after South Africa and Australia, accounting for 85% of US production. Most of the state's gold and silver comes from the prolific Carlin Trend and the parallel Battle Mountain - Eureka Trend. The Lewis property is strategically located within the Battle Mountain Trend, which hosts a range of mineral deposit types including high-grade vein-hosted gold deposits, large gold-copper porphyry systems with associated peripheral gold-silver skarns, and sedimentary-rock-hosted disseminated gold deposits. Mining commenced in the vicinity of the Lewis property in the 1860s with the exploitation of gold-silver lodes by surface- and underground-methods.
The Lewis property of Battle Mountain Gold Inc. (“the Company”) is located directly contiguous with the Fortitude - Phoenix mine placed into production by Newmont Mining Corporation in late 2006. The northern portion of the open-pit abuts the Lewis property. Future diamond drilling by Battle Mountain Gold Inc., which is scheduled to commence in mid-August 2016, will test from 200 m to 1,200 m from the margin of the Fortitude open-pit.
The Fortitude - Phoenix is one of the largest milling operations in the United States. Metals production in calendar 2015 from the Phoenix operations includes 205,000 ounces of gold, 46 million pounds of copper and by-product silver, and at December 31, 2015 reported proven and probable reserves of 5.1 million ounces of gold, 1750 million pounds of copper and 73.5 million ounces of silver, as indicated on pages 30 and 48 of Newmont’s 2015 Annual Report. The average grades associated with these stated reserve figures are 0.58 grams per metric tonne gold, 8.6 grams per metric tonne silver and 0.19% copper.
The high-grade portion of the Fortitude deposit was original mined by Battle Mountain Gold Company, a subsidiary of Duval Corporation. In January, 1985, the deposit reserves were reported as 11,684,000 short tons (10.6 million metric tonnes) at 0.154 troy ounces per ton of gold (5.28 grams per metric tonne Au) and 0.831 troy ounces per tonne of silver (28.5 grams per metric tonne Ag), as published in the Prospectus of Battle Mountain Gold Company in July, 1985. The ore in the original Fortitude mine consisted of calc-silicate and skarn-like calcareous rocks adjacent to the Tertiary Copper Canyon stock. These calcareous host-rocks are replaced by sulfide minerals which are associated with gold and silver in the form of electrum and silver-bearing sulfides. It is this style of higher grade gold-silver mineralization that the Company has targeted in its current exploration program.
Previous operators at Lewis focused their exploration efforts on the Virgin zone, a major structural-stratigraphic corridor which hosts the mineralization at Newmont's adjacent Fortitude - Phoenix mine. The programs of these companies confirmed that the Virgin zone extends onto the Lewis property within a similar geological environment, for up to 3 km of potential strike-length.
After securing an option to earn 60% of the Lewis property in 2002 (since earned), Madison Minerals Inc., the predecessor to the Company, focused its exploration on the Virgin zone and, to a lesser extent, the Buena Vista zone that lies about 500 m towards the west. From 2003 to 2008, Madison drilled 145 reverse circulation (RC) and 29 core holes totaling 36,100 m (118,100 ft) at the Lewis property, 167 of which tested the Virgin zone. Seven drill-holes tested the shallow portions of the Buena Vista zone. The vast majority of these 174 holes intersected gold-silver mineralization. One of the best results was obtained from a fault intersection along the Virgin zone, which returned high grades of 17.6 g/t gold and 48.1 g/t silver over 32 meters (105 ft; MAD-05).
In May 2014, Battle Mountain Gold Inc. executed a reverse take-over of Madison Minerals Inc. and commenced trading as BMG on the TSX-V. Through the completion of a private placement to Gold Standard Ventures Corp. and other subscribers in May 2016, the Company raised gross proceeds of about $5,769,000 Canadian. This placement and subsequent actions allowed Gold Standard Ventures Corp. to control more than 27% of the Company. Some of the funds generated through related actions led to the buy-down of the existing royalty for gold and silver on the Lewis property from 5% to 3.5% and the conversion from a gross royalty to a net smelter returns royalty.
The results of previous, recent and ongoing exploration programs will be used to generate an initial NI 43-101 compliant resource estimate for the Lewis property.
The Lewis property was historically mined for high-grade silver, gold and base metals and was first drilled in modern times by Hart River Mines (1980-1985). The discovery and development of a series of world-class gold deposits in the Carlin and Battle Mountain - Eureka Trends during the 1980s attracted several major companies to intermittently explore the Lewis Property, notably Homestake Mining, Santa Fe Pacific and the predecessor company of Barrick Gold. A subsequent round of exploration took place from 1996 to 1997, when United Tex-Sol Mines Inc. drilled holes UTX 1-16.
The Fortitude mine adjacent to the Lewis property was the most significant gold producer in the Battle Mountain Trend during the 1980s and became the flagship operation of Battle Mountain Gold Company, which was formed in December of 1984 to assume the gold mining operations of Duval Corporation. As Fortitude's high-grade reserves declined in the early 1990s, Battle Mountain Gold diversified from its namesake district to pursue projects worldwide. From 1984 to closure in early 1993, the Fortitude skarn deposit produced 2.8 million ounces of gold and 10.8 million ounces of silver from 11 million tons of ore, with heap-leaching of lower grade disseminated ores continuing until 2006.
Newmont Mining Corporation acquired the Battle Mountain Gold Company through a merger process completed in early 2001, and soon after reactivated exploration of the Phoenix deposit, the lower grade outer shell of the past-producing Fortitude mine. The newly constructed Phoenix Mine began operations in late 2006 in time to benefit from rising gold prices.
The intermittent exploration efforts of previous operators at the Lewis property during the 1980s and 1990s focused on the Virgin zone, a major gold-silver-bearing, structural-stratigraphic corridor which hosts the mineralization at Newmont's adjacent Fortitude mine. These early programs confirmed that the Virgin zone extends onto the Lewis Property within a similar geological environment, for up to 3 km of potential strike-length north of the claim boundary. Several parallel zones of mineralization were also tested. However, the majority of the drill-holes were completed to depths of less than 150 m.
2008 EXPLORATION PROGRAM OF MADISON
The 2008 drill program of Madison consisted of 17 core holes for a total of 3,855 meters and 33 RC holes for a total of 5,567 meters, which targeted the central portion of the Virgin zone and consisted of in-fill and step-out holes using a drill-spacing of 30 meters. The core drilling confirmed the previous RC results as well as the geological and structural models, while the overall drilling program expanded the Virgin zone by 100 meters down-dip over a 300-meter strike length. At year-end 2008, the northerly-trending Virgin zone was defined over a minimum 750-meter strike length and 350 meters east-west. The zone remains open for expansion along strike and down-dip to the west.
The 2008 drilling program also encountered significantly higher silver values. As an example, Hole MAD-145 intersected 1.21 g/t gold and 458 g/t silver over 6 meters, for a calculated equivalent of 7.17 g/t gold (at US$9 per ounce silver and US$900 per ounce gold) over the interval. These results suggest an apparent mineral zonation on the property, with silver values increasing to the north and west.
Results from the 2008 drilling program compare favorably with previously reported styles and grades of mineralization, including high-grade gold structural intersections, steeply west-dipping, mineralized zones and gently west-dipping, lower-grade mineralization hosted by reactive Antler Sequence stratigraphic units. The majority of the 2008 drill-holes intersected zones of gently-dipping, lower-grade mineralization.
Madison's exploration programs confirmed that the Lewis property shares a virtually identical geological environment to that underlying the Fortitude - Phoenix area, including the along-strike extension of the northerly-trending Virgin and Copper Canyon - Buena Vista zones and reactive Antler Sequence rock units. The southern boundary of the Lewis property abuts Newmont's present open pit, which means any new, or proposed, northerly or westerly expansion of this pit would require a push-back onto the Lewis property.
2014 – 2015 EXPLORATION PROGRAMS
The Company commenced its recent exploration of the Lewis property in late June, 2014. The field-work completed to date consists of detailed geological surface mapping (1:2,000-scale), geochemical rock- and soil-sampling, and re-logging of diamond-core and RC-chips from drill-holes completed by Madison Minerals Inc. from 2003 to 2008. The emphasis during this work has been on the geometric controls to gold-silver-and base metal-bearing fault and fracture systems. These target structures cut across several rock formations that have properties conducive to metals deposition, including the same Antler Sequence formations that host ore in the Fortitude mine of Newmont, located directly to the south.
At least eight mineralized zones were previously recognized in the Lewis property (refer to slides in the corporate presentation included in the Investor Info – Presentations section of the web-site and corporate press-releases from June, 2014 to recent). The best understood gold-silver systems to date include the Virgin, Buena Vista, Meagher - Silver, White - Shiloh and Trinity zones, which are open along strike and at depth. Gold- and silver-bearing portions of these zones exceed 1,200 m for the Virgin; 1,300 m for Buena Vista; 650 m for Meagher - Silver; 900 m for White - Shiloh; and 1,700 m for Trinity. Recent geochemical sampling of these zones and news areas of mineralization indicate rock results of up to 99.9 g/t Au, 5600 g/t Ag, 11.8% Pb and 6.2% Zn. Individual sample assay results are described in the rock-chip database included in the Investor Info – Presentations section of the web-site. The samples were collected from steeply dipping, northerly- and northwesterly-striking fault and fracture zones that are typically illitic clay-altered and characterized by iron-oxides that have formed from the weathering of pyrite, galena, sphalerite and locally arsenopyrite. The outcrop samples are from zones 1 to 5 m wide that lie within broader belts of structure / hydrothermal alteration up to 75 m wide.
The results of 201 rock samples collected over the property as of June, 2015 are summarized as follows: Gold – 89 samples (44 % of all samples) contain > 1 g/t; 26 yield > 5 g/t; 11 contain > 10 g/t with maxima of 99.9, 53.4, 36.8 and 24.7 g/t Au. Silver – 90 samples (45 %) contain > 50 g/t; 43 yield > 200 g/t; 17 contain > 500 g/t with maxima of 5600, 3620, 1810 and 1695 g/t Ag. Lead and Zinc – 73 samples contain > 1 % Pb with a maximum of 11.8 %; 16 samples return > 1 % Zn with a maximum of 6.2 % Zn.
Silver values in rock up to 5600 g/t Ag and gold results up to 13.2 g/t Au characterize the Meagher - Silver zone in the western part of the property. This zone consists of two north-trending and west-dipping faults, each more than 650 m long. These mineralized structures and those of the Buena Vista system, with surface values of up to 24.7 g/t Au and 359 g/t Ag, extend to the south into the Fortitude copper-gold-silver mine. The intersection of these mineralized structures with the reactive rocks that host ore in the Fortitude deposit represents an attractive drill target that lies from 100 to > 300 m beneath surface in the Lewis property.
In late-2014, a total of 466 soil samples were collected along traverses oriented across the northerly-trend of the Trinity system in the southeastern part of the claim area. The samples are spaced every 8 m (25 ft) with every two samples composited to form 233 assay samples for a nominal spacing of 16 m (50 ft). The assay results indicate high values for gold, silver lead and zinc. The combined gold (Au > 100 ppb) and silver (Ag > 5 ppm) soil anomaly is localized along a north-northeasterly trending portion of the Trinity fault zone and exceeds 1,700 m in strike-length with widths of up to 200 m. This anomalous gold-silver zone is supported by a coherent lead and zinc anomaly, using thresholds of 300 ppm Pb and 300 ppm Zn. Rock chip samples from the Trinity return up to 14.1 g/t Au, 1490 g/t Ag, 5.4 % Pb and 1.6 % Zn (see rock-chip sample database for individual sample assay results). Future work in this area will focus on follow-up surface mapping and drill target delineation.
Hyperspectral imagery (HSI) was acquired over the Lewis property and portions of the adjacent Newmont mine operations on July 13th, 2014 by SpecTIR LLC using an AISA Eagle/Hawk Dual (Dual) hyperspectral camera system carried by a light aircraft. Approximately 65 Km2 of data were acquired with a nominal ground resolution of 2 m. The Dual system acquired 360 spectral bands between 400 and 2,450 nanometers with spectral resolutions ranging from the visible to shortwave infrared. Similar types of hyperspectral analysis have delineated mineral zoning and directions to ore-bearing structures in gold- and silver-bearing deposits elsewhere in Nevada (e.g., Goldfield), Utah (e.g., Tintic District) and Mexico (e.g., Fresnillo region). A ground-based spectroscopy survey was completed in support of the airborne survey, during August, 2014. A total of 272 surface samples and 81 drill-core samples were analyzed using a TerraSpec Pro spectrometer.
The results of the airborne- and ground-surveys have been integrated with local geology to produce a coherent interpretation over the project area. In gold- and silver-bearing structural zones, HSI illite commonly occurs with HSI hematite and jarosite, which are iron-oxide minerals that developed from the weathering of sulfide minerals. There is a close spatial coincidence of HSI hematite and jarosite to known prospects and structures. The combined spectral surveys identified new zones of exploration interest, some of which are characterized by ammonium-illite. Ammonium-illite has the potential to delineate structures that tap gold-rich zones at depth, as indicated for Carlin-type gold deposits in Nevada (e.g., Goldstrike and Jerritt Canyon) and epithermal gold deposits in Argentina (e.g., Esquel). Hematite typically occurs within zones of ammonium-illite hosted in the Nevada Carlin-type deposits. Follow-up sampling of these ammonium-illite anomalies have produced targets at Galena and the Apex antimony mine, which are characterized by surface rock-chip results of up to 3.1 g/t Au, 353 g/t Ag, 1% As and > 1 % Sb (see rock-chip sample database for individual sample assay results).
During late-2014, the Company completed the digitizing of down-hole geology logs and multi-element assays for about 280 drill-holes completed by Hart River, Barrick and Sante Fe during the 1980s and 1990s. Most of the added holes are less than 150 m deep and collared in the Trinity, White - Shiloh, Hider and Circle Peak areas. The current digital drill-hole database, which includes 224 drill-holes in the Virgin - Buena Vista area, now totals approximately 500 drill-holes. The incorporation of this historic data into the Lewis property digital database has assisted in the creation of 3D geological models for mineralized structures and favorable rock units in the southern part of the claim area.
Also during late-2014, a total of 14 diamond drill-holes were re-logged from the Virgin area for a total of 3,200 m or 50 % of the drill-core collected by Madison Minerals Inc. during 2003 to 2008. In mid-2015, RC-chips from 48 holes were re-logged for 10,800 m or 38% of the RC-chips available. The focus of the re-logging campaign was to better define lithology, hydrothermal alteration, sulfide mineralization and structure in drill-hole and to ensure consistency with the surface mapping recently completed by the Company. The integration of the results of the re-logging program with the district-wide drill database has enabled the construction of about 50 west-east oriented geological cross-sections.
Three-dimensional imaging of geophysical results from a Quantec TITAN - IP survey from 2003 and a Zonge IP survey from 2007 completed over the Virgin and Buena Vista areas was undertaken in late-2014. The magneto-tellurics (MT) data from the Quantec survey were re-processed by SourceOne Geophysical using modern algorithms in the 3rd Quarter of 2015. This reprocessing has improved the resolution of the results and sharpened resistivity boundaries, which has assisted in the understanding of the 3D geological models and drill-target delineation.
The integration of the updated and revised digital drill database and re-processed geophysical data with the results of surface mapping and geochemical sampling has served as the basis for the creation of comprehensive 3D models for the southern portion of the Lewis property. The geological portions of the models were created through collaboration with SRK Consulting (Reno) using LeapFrog software in the 3rd Quarter of 2015. The understanding gained through the creation of these models has assisted the Company in the generation of several high-grade gold-silver targets. The most compelling of these targets lie in the Virgin, Buena Vista and Meagher - Silver structural zones in the southern part of the Lewis property.
2016 EXPLORATION PROGRAM
A helicopter-borne magnetic and radiometric survey was flown over the project environs by Precision Geosurveys during June, 2016. The survey covered about 110 km2 for a total of 1270 line-km, consisting of east-west oriented flight-lines spaced 100 m apart and north-south tie-lines spaced every 1000 m. The survey was flown at a nearly constant height of 25 meters above the ground. The magnetic results indicate zones of high magnetic intensity over known intrusions. In addition, these results delineate two major east-northeasterly-trending lineaments that coincide locally with the distribution of variably clay-pyrite-altered, Tertiary dikes and fracture zones. These dikes and fracture zones are associated with gold-silver mineralization in the southern part of the Lewis property and in the northern portion of the Fortitude deposit. One of the magnetic lineaments intersects, and changes trend across, the Buena Vista fault zone. This magnetic-structural intersection lies adjacent to the convergence of the Buena Vista, Meagher, Silver and Theodore fault zones, which will be tested by a diamond drilling program. The processed images of the radiometric results show a good spatial coincidence between gold-silver bearing fault zones and radiometric gradients. This is consistent with the fault juxtaposition of host-rock units that contain varying abundances of radiometric potassium, thorium and uranium. Further details and images of the relationships between the results of the 2016 geophysical surveys are contained in the corporate presentation and a separate report prepared by Fathom Geophysics, both of which are included in the Investor Info – Presentations section of the Company web-site.
A ground-based gravity survey was completed over the 22.25 km2 Lewis property in late May, 2016 by Magee Geophysical Services for a total of 289 stations. Processing and imaging of the results indicate that some of the major gold-silver-bearing fault zones coincide with gravity gradients. This is due to the fault juxtaposition of rock units characterized by contrasting density (specific gravity). Many of the gradients expressed by the gravity results coincide with gradients observed in the magnetic- and radiometric-results and mapped faults. The spatial coincidence of geophysical gradients with known gold-silver-bearing fault zones will assist the Company in targeting large and potentially well-mineralized structural zones for future exploration and drilling. The collection of about 500 more gravity stations was accomplished in early August, 2016, with the aim to improve data resolution and the extent of coverage.
The re-logging of diamond drill-core and reverse-circulation (RC) chips have continued in 2016. An additional 13 diamond-core holes were re-logged in late May to July, to bring the project total to 27 core-holes for about 6500 m. The re-logging of RC chips re-commenced in late July, with plans to bring the project total to about 85 holes for > 18,500 m. The primary aims of the re-logging program are to better define geology and mineralization in drill-hole and improve the three-dimensional geological and structural models for the project area, particularly for the Virgin zone. The majority of the planned RC chip re-logging will be completed prior to the start of diamond drilling.
The most compelling exploration targets delineated to date lie in the Virgin, Buena Vista and Meagher - Silver areas. These targets will be tested by a twelve-hole diamond drill-program exceeding 5,000 meters and is scheduled to start in mid-August, 2016. Many of the planned drill-holes will also test geophysical gradients and anomalies. Attractive targets exist in the Galena, White - Shiloh and Trinity systems, which are intended for drill-testing in 2017. Any additional targets generated by the recently completed geophysical programs and future soil-grid work will be advanced to the drill-stage through surface mapping and geochemical sampling.
The grid-soil sampling of portions of the southwestern part of the claim area commenced in early August, 2016. The purpose of the survey is to further delineate the surface expression of gold-bearing fault zones using a multi-element geochemical approach. For example, previous drilling by Barrick Gold (1987) in this area indicates 16.7 m at 5.86 g/t Au and 0.2% Cu from 775.7 m in FWL-30, hosted by skarn in the Antler Limestone that lies beneath the Golconda Thrust. Previous work by the Company indicates that gold-silver-bearing target zones, contained within reactive, Antler Sequence host-rocks beneath the Golconda Thrust, are typically expressed by multi-element anomalies in the Havallah / Pumpernickle Formation at surface. These surface anomalies are characterized by elevated arsenic, bismuth, low-level gold and silver, and other pathfinder elements. The grid soil-survey will cover portions of the 4 km2 area of interest.
Geological mapping (1:2,000-scale) and geochemical rock sampling are ongoing in the Lewis property. Recent work has focused on the eastern portion of the claim block, along a northerly-trending, gold-silver-arsenic-bearing structural corridor that extends from the inactive Iron Canyon gold-silver mine in the south through the historic Apex antimony mine to the Antimony King mine in the north. This style of mineralization is associated with northerly-trending, clay-altered Tertiary dikes of similar composition to those that occur in the Fortitude - Phoenix mine area.
The technical information in this website about activities on the Lewis Project from June 1, 2014 onwards has been prepared by the Company’s Qualified Person, Steven Garwin, Ph.D., a director of the Company, a Fellow of the Australian Institute of Geoscientists and a Fellow of the Australasian Institute of Mining and Metallurgy. The technical information in this website on activities on the Lewis Project prior to June 2014 is based upon a report under National Instrument 43-101filed on SEDAR March 31, 2014 and titled AMENDED AND RESTATED SUMMARY REPORT 2007-2008 CORE AND REVERSE CIRCULATION DRILLING PROGRAM, F.W. LEWIS PROPERTY, BATTLE MOUNTAIN MINING DISTRICT, LANDER COUNTY, NEVADA, USA (the “2014 43-101 Report”). Dr. Garwin has reviewed the 2014 43-101 Report and has approved the written disclosure drawn therefrom set out in this website.