Overview
Stage | Preliminary Economic Assessment |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Heap leach
- ROM/dump leach
- Carbon in column (CIC)
- Carbon adsorption-desorption-recovery (ADR)
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Mine Life | 8 years (as of Jan 1, 2018) |
On August 31, 2021, the Company acquired the Bruner Property, located in Nye County, Nevada, from Canamex Gold Corp. (“Canamex”).
A historic resource estimate of 342,000 oz of gold contained in 17.5 million tonnes grading 0.61 gpt Au, was prepared for Canamex in a technical report dated January 22, 2018 titled “NI 43-101 Technical Report on the Bruner Gold Project, Updated Preliminary Economic Assessment, Nye County, Nevada, USA” by Welsh Hagen Associates. A “qualified person” (as defined in NI 43-101) has not done sufficient work for the Company to classify the historical estimate as a current mineral resource or mineral reserve. The Company is not treating the historical estimate as a current mineral resource or mineral reserve, has not verified the historical resource estimate and is not relying on it. |
Latest News | Endeavour Silver Completes Acquisition of Bruner Gold Project in Nye County, Nevada September 1, 2021 |
Source:
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Vancouver, Canada – September 1, 2021 – Endeavour Silver Corp. (TSX: EDR, NYSE: EXK) (“Endeavour”) is pleased to announce that it has completed the acquisition of the Bruner Property, located in Nye County, Nevada, from Canamex Gold Corp. (“Canamex”). Endeavour paid US$10 million in cash for 100% of the Bruner Gold Project which includes mineral claims, mining rights, property assets, water rights, and government authorizations and permits.
Deposit Type
- Epithermal
- Vein / narrow vein
Summary:
Gold and silver at the Bruner property occur within narrow quartz + adularia +/- pyrite veins and veinlets, along fractures, and in disseminations that are manifested as sheeted/stockwork zones, vein swarms, and rare 0.3-2 meter wide veins, hosted by high-silica rhyolite flow domes and encasing and surrounding volcaniclastic units that overlie a mostly unaltered andesite base. The mineralization style is classified as low-sulfidation epithermal (LSE) with occasionally highgrade gold+quartz+adularia veins occurring within broad zones of hydrothermal alteration containing low-grade gold and silver.
Three zones of gold-silver mineralization have been outlined by drilling: the Historic Resource Area, and the Paymaster zone, which are located on patented mining claims, and the Penelas Zone, including both the historic Penelas Mine and the relatively newly discovered Penelas East area, which is located entirely on unpatented mining claims. All three areas have seen limited mining activity and production in the past, largely by selective underground methods.
Outcrop in the Historic Resource Area is dominated by moderately (30-55°) north-dipping biotite-rich Tbl rocks with intruding rhyolite dikes (Tr1) and rare occurrences of rhyolite tuffisite dikes (Ttd) and mafic intrusive rocks (Tba).
Structural measurements from the Historic Resource Area show that veins, faults, and joints are consistently north-trending and steeply-dipping and display normal and dextral-normal slip (Dering, 2014). Surface and underground mapping highlight older northwest-trending faults that are offset by these north-trending structures. The weak surface expression of these structures suggests slip on the north-striking structures has been tens of meters or less.
Textural evidence suggests that acanthite was partially leached out of primary electrum + acanthite assemblages in the Historic Resource Area. Although gold is typically hosted within and adjacent to high-angle structures the morphology of a widespread halo of lower-grade goldbearing rock subparallel to the current topography is present in the Historic Resource Area. The Ag:Au ratio is highly variable throughout the Bruner property and pervasive oxidation of the host rocks in the Historic Resource Area is extensive, all indicating that supergene remobilization of silver ± gold likely occurred.
Underground mapping at the Paymaster Mine revealed moderately-dipping (50-75°) north- to northeast- trending structures, and a series of shallow- dipping (30-40°) listric faults.
At Paymaster the host rocks are similar to those in the Historic Resource Area, where mineralized zones are concentrated in fractured, silicified, and adularized biotite-rich Tbl rocks. Rocks mined from the Paymaster Vein in the historic Paymaster Mine are described as fragmented vein material, analogous to some ore material mined at July-Duluth in the Historic Resource Area. Mineralized rocks at Paymaster are located just above the Tbl/Ta contact and appear to be confined by the underlying Ta unit. Based on recent and historic drilling this contact appears to be shallow- dipping and moderately offset structurally, creating a relatively flat-lying mineralized zone compared to other areas of the Bruner property.
The Penelas Area hosts the Penelas Mine, which is historically the most productive mine in the Bruner district. The Penelas East Area is a newly discovered zone approximately 400 meters east of the historic Penelas Mine. The host rocks at Penelas East are similar to those found at the Penelas Mine.
Gold- and silver-bearing veins and veinlets in the Penelas Mine Area occur along a northstriking, moderately east-dipping fault in Trp rocks forming the Penelas Vein. The Penelas Vein is 1-2 meters wide and has a strike length of at least 500 meters. Historic workings followed this vein to at least 300 meters depth in the Penelas Mine. Mineralized intervals contain electrumand acanthite-bearing quartz + adularia (up to 50%) veinlets and veins with lesser illite, montmorillonite, amethyst quartz, and iron-rich micas. Mineralized structures display textures indicative of open-space filling and boiling including colloform banding, bladed quartz and adularia after calcite, and vugs. Some structures contain fault breccias with mineralized vein fragments similar to parts of the Historic Resource Area (e.g. the Crag Fissure). Importantly, gold- and silver-bearing veins are not commonly found away from the Penelas Vein in the Penelas Mine Area.
Mineralized zones in the Penelas East Area are hosted in Trp rocks similar to the Penelas Mine. At the Penelas Mine gold-bearing veins occur in a discrete vein zone (i.e. the Penelas Vein), though at Penelas East gold-bearing veins form stockwork zones of 1-10 mm quartz + adularia + iron oxide (± illite ± montmorillonite ± amethyst quartz ± iron- rich micas) veinlets. Iron oxide minerals include hematite, goethite, and limonite and are interpreted to have formed, in part, by oxidation of vein-hosted pyrite. In the Penelas East Area these stockwork vein intervals have been intersected at multiple levels in the stratigraphy, unlike at the Penelas Mine, along a series of steeply-dipping structures. The Penelas Mine and Penelas East Areas are cutoff to the south by a major northwest-trending down-to-the- northeast structure that continues to the south of the Historic Resource Area.
Summary:
The mining operation is assumed to be a conventional open pit mine, with drill and blast rock breakage and truck and loader materials handling.
The mine production schedule was based on an average of 7,500 tonnes/day delivered to the crusher and lower grade ores being placed directly on the heap leach pad as run of mine (ROM) ore. WHA opted to take the mineralized material between 0.117 and 0.192 gold equivalent and treat it as run of mine material, that is, not crush it prior to stacking on the pads. The pits will be mined sequentially beginning at the Paymaster pit and progressing southeasterly to the HRA and Penelas pits. The production schedule was constrained to produce a constant feed of mineralized material to the crusher and conveyor loading onto the heap leach pad. ROM ores will be stacked on the heap leach pad without crushing. The ratio of ROM ore to crushed ore may vary due to gold price, ore grade, crushing costs, and recovery projections. Based on the high leachability of the mineral deposits, it is probable that a high percentage of the ore will be placed as ROM ore. Some stockpiling of higher grade material may be required to balance the crusher feed rate.
No site specific geotechnical studies have been undertaken to date, other than the kinematic structural analysis completed by Dering (2014), and therefore pit slopes were based on reasonable assumptions and observation of nearby operating surface mines. An overall pit slope of 55° was used for pit optimization. This is typically an attainable pit slope in volcanic rocks for open pit mines in Nevada unless there are unfavorable faults, fracturing, or weak zones of alteration. Dering’s 2014 study supports a 55 degree pit slope for the Bruner property.
Mineral resources within the pit volume were evaluated and scheduled out using an Excel spreadsheet. The average cutoff grade for the mine life of the potential mining project was 0.192 Au g/t for crushed ore and 0.117 g/t for ROM ore.
The contract haulage fleet will need to move approximately 7,500 tonnes per day of ore and approximately 30,000 tonnes per day of waste. This will likely be done with trucks in the 80 to 90 tonne range and appropriately sized wheel loaders. Ancillary equipment will include water trucks, dozer(s), grader(s), blast hole drills, a service truck, and a fuel/lube truck.
At the crusher, the Owner will provide a front-end loader to feed the crusher from the coarse ore stockpile when trucks are not direct dumping. A D-6 size dozer will also be needed on the heap leach pad to spread ROM ore and level the surface of the crushed ore for leaching.
Flow Sheet:
Crusher / Mill Type | Model | Size | Power | Quantity |
Jaw crusher
|
|
|
|
1
|
Summary:
As shown in Process Flow Sheet, option A would be to install a jaw crusher to crush the ore to a nominal 4-inch size prior to loading it onto the heap pad.
Processing
- Heap leach
- ROM/dump leach
- Carbon in column (CIC)
- Carbon adsorption-desorption-recovery (ADR)
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Flow Sheet:
Summary:
Based on proximity to surface, average grade and the results from preliminary metallurgical test work, the recovery methods anticipated to be most appropriate for the Bruner Gold Project are cyanide heap leach with carbon adsorption. A zinc precipitation (Merrill-Crowe) recovery process was not deemed to be needed due to the low silver recovery observed in the metallurgical testing results.
The process will use heap leaching with a standard “adsorption-desorption-recovery” (ADR) process for recovering the solubilized gold (and silver) from the leach solutions. As shown in Process Flow Sheet, option A would be to install a jaw crusher to crush the ore to a nominal 4-inch size prior to loading it onto the heap pad; option B would be to haul “run-of-mine” ore directly to the heap. The cyanide solution from the Barren Pond is percolated through the heap to create the Pregnant Leach Solution (PLS) that is collected at the bottom of the heap. The PLS is then pumped through activa ........

Recoveries & Grades:
Commodity | Parameter | Avg. LOM |
Gold
|
Recovery Rate, %
| 89.6 |
Gold
|
Head Grade, g/t
| 0.56 |
Silver
|
Recovery Rate, %
| 10 |
Silver
|
Head Grade, g/t
| 5.2 |
Projected Production:
Commodity | Units | LOM |
Gold
|
oz
| 349,300 |
Silver
|
oz
| ......  |
All production numbers are expressed as metal in doré.
Operational Metrics:
Metrics | |
Daily mining rate
| 37,500 t * |
Daily ore mining rate
| 7,500 t * |
Waste tonnes, LOM
| 65,200 kt * |
Ore tonnes mined, LOM
| 21,800 kt * |
Total tonnes mined, LOM
| 87,000 kt * |
* According to 2018 study.
Reserves at December 26, 2017:
Resources are reported using a 0.006 oz/t (0.192 gpt Au equiv.) gold cut-off grade for crush material, and a 0.004 oz/t (0.117 gpt Au equiv.) gold cut-off grade for crush material above internal breakeven but below external breakeven cutoff.
Category | Tonnage | Commodity | Grade | Contained Metal |
Indicated
|
19,550 kt
|
Gold
|
0.56 g/t
|
353 koz
|
Indicated
|
19,550 kt
|
Silver
|
5.32 g/t
|
3,342 koz
|
Inferred
|
2,250 kt
|
Gold
|
0.53 g/t
|
38 koz
|
Inferred
|
2,250 kt
|
Silver
|
4.14 g/t
|
299 koz
|
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