In 2014, the Company reported an updated Life of Mine Plan ("LOM Plan") for the Mineral Ridge Operation that included the Drinkwater, Mary, Mary LC, and the five satellite deposits, Brodie, Bluelite, Solberry, Wedge and Oromonte (see July 21, 2014
news release and Mineral Reserve & Resource Estimates
). The Company's more recently updated mine plan includes the Mary LC, Bluelite, Solberry, Missouri and the Brodie phase B pits. To date, the Drinkwater, Bluelite, Solberry and Wedge pit resources have been depleted. Scheduled mining continues in the Mary LC, Missouri, Brodie SE and Brodie Phase "B" pits.
Permitted mining at Mineral Ridge remains scheduled to end in mid-2017. The Company is seeking approval from the Nevada Bureau of Land Management for its Environmental Assessment application to open pit mine the Custer and Oromonte deposits, which could extend the mining schedule.
Diamond drilling in 2016 will further evaluate the economics of the NW Drinkwater Highwall and Bunkhouse Hill areas, which if successful could also extend the mining schedule. In addition, an increase in the price of gold is allowing the Company to re-evaluate outlined mineralization sources within its permitted mining boundary that were previously deemed uneconomic.
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Operations Area Map
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Operations Area Map with Drill Hole Locations
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Mary - Mary LC Deposit
The historic Mary deposit is located immediately southeast of the Drinkwater pit. Scorpio Gold commenced production at Mary in 2012. Exploration drilling in 2011 indicated that the gold mineralization extended further southeast from Mary to the adjacent Mary LC zone, encompassing a strike length of 780 meters. Subsequent work determined that the Drinkwater, Mary and Mary LC zones were not isolated deposits but represented one continuous zone of mineralization.
Drilling in 2012-2013 led to the completion of a mineral reserve and resource estimate for the Mary - Mary LC and incorporation of the expanded pit design into the updated LOM Plan. Infill and step-out drilling on the Mary LC post the March 31, 2014 cut-off date of the LOM Plan focused on increasing the total mineral resources, upgrading resource categories, lowering the strip ratio. Commercial production the Mary LC pit was achieved in 2015.
Mary LC Drill Plan
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The satellite Brodie, Bluelite, Solberry, Wedge and Oromonte deposits are situated west and southwest of the Drinkwater pit and lie in close proximity to the leach pad. These deposits are part of a semi-continuous trend of mineralization within a shallow-dipping stratigraphic horizon. They lie on the western flank of an anticlinal fold structure and are considered to be related to mineralization within the Drinkwater-Mary-Mary LC trend, which lies on the eastern flank.
Drilling on the satellite deposits post the LOM Plan cut-off date included infill, development and exploration drilling to expand and upgrade the mineral reserve and resource base and potentially extend life of mine.
Brodie, Bluelite & Missouri Deposits
The Brodie and Bluelite deposits are located 975 meters (3,200 feet) and 1,100 meters (3,600 feet) southwest, respectively, of the Drinkwater pit. The 500 meter (1,640 feet) mineralized corridor that lies between the Bluelite and Brodie deposits is known as the NW Brodie trend. Commercial production in both the Brodie and Bluelite pits was achieved in 2015. The Bluelite pit resources have since been depleted.
The Missouri is a shallowly northeast dipping deposit located west and northwest of the Brodie deposit. It outcrops at surface and has some historical underground workings. The mineralization has been outlined by drilling over a ~200 meter strike length and ~100 meters down dip with true widths ranging from 1.5 to 7.62 meters. Scorpio Gold commenced open pit mining of the Missouri deposit in Q2 2016.
Brodie Drill Plan
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Bluelite Drill Plan
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NW Brodie Trend & Missouri Deposit Drill Plan
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The Solberry deposit lies west of the Drinkwater pit and 600 meters (1,970 feet) northwest of the leach pad. Drilling in 2014-15 successfully upgraded the resource base at Solberry and commercial production was achieved in 2015. The Solberry pit resources have since been depleted.
Solberry Drill Plan
(PDF 1.5 Mb)
The Wedge deposit is located 225 meters (740 feet) southwest of the Drinkwater pit and immediately adjacent to the leach pad. Positive results from the 2014-15 expansion drilling program successfully upgraded the resource base at Wedge and commercial production was achieved in 2015. The Wedge pit resources have since been depleted.
Wedge Drill Plan
(PDF 1.5 Mb)
The Oromonte target occurs over a 300 x 500 meter area situated between the Solberry and Wedge deposits. A small mineral resource estimate for the deposit based on 53 RC drill holes was reported in the 2014 LOM Plan. Follow-up drilling in 2014-2016 intersected significant mineralization at vertical depths ranging from near surface to 150 meters depth across the target area.
The mineralization at Oromonte is interpreted to be a continuation of the mineralized horizon(s) between the Solberry and Wedge deposits that have been offset by normal faulting. The occurrence of a higher-grade zone of mineralization at depth is thought to be related to a rheological contrast between the basement granite and a later intrusion of alaskite (leucogranite). The difference in deformational behaviour of the two rock types under stress may have caused greater structural damage and fluid flow within the mineralizing structures in this area, resulting in a higher-grade zone of mineralization. The Oromonte deposit was subsequently down-dropped by late-stage normal faulting. A generalized geological model of the mineralization is presented in the Oromonte Cross Section.
Although not accessible by open pit mining, the deeper mineralization at Oromonte may be amenable to underground extraction should further results support underground development. Historical underground workings occur in the Wedge deposit area approximately 180 meters to the east.
Oromonte Drill Plan
(PDF 2.2 Mb)
Oromonte Cross Section
(PDF 350 Kb)
Discovered in 2015, the Custer deposit lies along trend of and ~500 meters southeast of the Mary LC deposit. Structurally, Custer is very similar to the Drinkwater deposit, having far less of the post-mineral faulting and folding that was predominant in the Mary and Mary LC deposits. As a result, the mineralization at Custer is quite continuous and predictable. Definition drilling in 2016 followed up on a highly successful first-pass drilling program in 2015. A total of 81 holes have now outlined the Custer mineralized zone over a 150 x 200 meter area at depth (see May 3, 2016
news release). The deposit is under an internal economic evaluation including reserve and resource estimation and is potentially slated for open pit production in 2017, pending permitting.
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