Based on current published explanations for the Mineral Ridge mineralization, it appears that astructurally-controlled orogenic model may be the most applicable to the deposit.

The currently-known mineralized zones occur over an area of approximately 14,000 ft (4,300 m) north south and 15,000 ft (4,600 m) east–west. The gold mineralization at Mineral Ridge is primarily associated with milky quartz veins and lenses accompanied by local argillization and some sericitization. Prior to mining, the individual zones were as much as 50 ft (15 m) thick, typicallyconsisting of a higher-grade quartz veins from five to 30 ft (9 m) thick, surrounded by a lower-grade envelope of mineralization. Two or more highgrade zones are commonly observed stacked in en echelon patterns.

Gold deposition is structurally-controlled, and some of the highest-grade mineralization is found in shoots that are at an oblique angle to the direction of movement of extension. Gold is present as native gold and electrum that occurs as irregular shaped intergrowths in quartz associated with interstitial space and small fractures. Gold also occurs as irregularly-shaped intergrowths and as fracture fillings associated with goethite, much of which was derived from original pyrite. In partially oxidized mineralization, gold occurs with both pyrite and goethite. Gold particle size varies from 1–2 µm to about 700 µm, but most of the particles are in the 5–50 µm size range. Gold to silver ratios are typically in the 2:1 range. Locally, minor amounts of galena, graphitic to carbonaceous material, sphalerite and anglesite/cerrusite have been observed, with galena and graphite appearing to be associated with higher-grade gold values.

Much of the known mineralization has been mined out in the Drinkwater, Mary LC, Wedge A, B, C, and D, Bluelite, Solberry, Missouri, Brodie, and underground portion of the Oromonte areas. Five areas of remnant mineralization adjacent to the Drinkwater, Mary LC, Bunkhouse Hill, and Brodie open pits are considered to remain prospective for remnant open pit mining, as is the Custer area, which has no open pit mining history, situated to the southeast of Bunkhouse Hill. Four of these areas are on the eastern, Drinkwater, side of the Mineral Ridge antiform (Drinkwater, Mary LC, Bunkhouse Hill, Custer), and two, Oromonte and Brodie, are on the western limb of the antiform.

Drinkwater
An area remains to the northwest of the Drinkwater deposit, and currently forms the highwall of the Drinkwater pit. The mineralized zones in the Drinkwater deposit strike northwest–southeast and dip about 20–25º to the northeast. Mineralized zones are irregular in shape, and have variable thicknesses. In the Drinkwater remnant area, there is a thick sequence of waste material that will require pre-stripping to access the mineralized horizon.

Mary LC ( Mary LC Phase 4 Pit)
The Mary LC deposit is located about 500 ft southeast of the Drinkwater deposit. The stratigraphy and mineralized horizons dip to the northeast at approximately 25º. The fourth proposed pit phase would extract mineralization contained in a zone on the northwest pit highwall.

Bunkhouse Hill
Geologically, the Bunkhouse Hill target is the immediate down-dip extension of the mineralization present in the Mary LC pit. The mineralization at Bunkhouse dips at about 39º NE, which is incontrast to the more typical 25–30º NE dip of the Mary LC mineralization. This dip change is spatially related to a change in geology, whereby the mineralized zone transitions from being hosted in felsic intrusive rocks to being hosted in Wyman Formation sedimentary rocks.

Custer
The Custer zone is situated south of the Mary open pit and the Bunkhouse Hill area. 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 Last Chance deposits.

Brodie (Brodie Phase 2 Pit)
Mineralization at Brodie is more flat-lying than mineralization at Drinkwater and Mary.

Oromonte
Mineralization at Oromonte is located north of the Brodie pit area. Mineralization occurs in a downdropped block located between the mined-out Solberry and Wedge pits.

There are two elements to the proposed mining methods for this study. The first area involves the mining of the previously-processed heap leach material and processing it though a milling facility. The second item involves the mining of remnant areas adjacent to existing open pits on the property and sending this material to the new process facility. The milling facility will have a higher gold recovery than the heap leach process, so the remnant areas have become economic to mine.

Production of mineralized material from the heap and pit area is planned at a nominal rate of 4,000 t/d. Due to the timing of building a new pad storage area for the heap leach material, the heap leach material has to be processed before the mining of the pit areas to allow room for the additional material from the open pits. Mining and processing of the heap ore will take a little over five years and mining and processing of the open pit ores will take three years for a total projected mine life of 7.5 years.

LEACH PAD
Mill feed material is derived from moving the previously-processed heap leach material from the existing heap leach to a mill facility, to process and reclaim economic material from the leach material.

No drilling or blasting is anticipated as the reclaim leach material is unconsolidated. All material movement will consist of transporting the reclaim leach material from the existing heap leach pad to the mill facility. A hopper and solution mixing system will be constructed on the leach pad in order to pump material directly from the leach pad to the mill. After materials are processed through the milling operation, the tailings leaving the mill will be placed back on the pad using conveyor stackers.

To convey the reclaim material from the pad to the mill, the material will be mixed into a slurry using a mixing system constructed on the pad. The mixing system will comprise a hopper, a mixing tank, pumps and piping. To remove ore from the pad, a 10 yd3 front-end loader (CAT 988K or equivalent) will load reclaim leach material into the hopper. Reclaim material within close proximity to the hopper/conveyor system will be pushed with a dozer (CAT D8T or equivalent) such that the front-end loader can load the material. A 50 yd3 scraper (CAT 637K or equivalent) will load and haul material that is located further away from the hopper and dump it near the hopper. Reclaim material will generally be removed from the top down, proceeding west to east and south to north.

REMNANT MATERIAL
The Mineral Ridge deposits contain mineralization at or near the bedrock surface that are ideal for open pit mining methods. The method of material transport at Scorpio Gold will be open pit mining using two to three 16-yd3 front-end-loaders as the main loading units; a 6.6-yd3 excavator will be used for sorting out narrow ore zones. The open pit mineralized material will be loaded into 100-t haul trucks and transported to the crushing site next to the mill. Waste material will be transported to a designated WRSF for each pit.

Mining is currently planned on 20 ft levels, but areas that contain ore zones are designed to be mined in approximately 10 ft levels. All blasting will be conducted per MSHA regulations on mines and mining plants. Blastholes 6.75 inches in diameter will be drilled on an approximate 13 ft x 14 ft staggered pattern for a 20 ft bench in the non-mineralized area. Blastholes 4.5 inches in diameter will be drilled in the mineralized zones on an approximate 10 ft x 11.5 ft staggered pattern on 10 ft. benches. All material will be blasted, generally using ANFO, with up to approximately 20% of the blasting requiring emulsion for better fragmentation and possible wet holes due to precipitation.

Pit Design.
A total of 51 pit shells were generated to determine optimal break points in the pit phases and the final pit phase for each deposit. The Oromonte pit was designed in two phases, due to the large strip that would be required for this area. All other areas were designed in one pit phase, but the Custer, Mary LC and Drinkwater areas were designed with two different pits. The Custer pit has small satellite pit referred to as the South Custer pit, the Mary-LC pit has a small satellite pit referred to as the West Mary pit, and the Drinkwater pit has a small satellite pit referred to as the South Drinkwater pit.

Haul roads are designed at a width of 80 ft, which provides a safe truck width (21 ft wide for 100- ton vehicles) to running surface width ratio of 1:3.5. Maximum grade of the haul roads is 10%, except for the lower benches where the grade is increased to 12%, and the ramp width is narrowed to 60 ft to minimize excessive waste stripping.

Generally, the evaluations concur that bench face slope angles of 70–75º with 15 ft wide benches from 15 ft to 20 ft bench heights. East-facing pit slopes, where bedding generally dips away from the pit wall are recommended by AMEC to have a flatter configuration of a 70º inter-bench face slope and 15 ft wide benches every 15 ft in elevation.

The current Drinkwater pit has a high wall of an approximate 400 ft height which shows no significant signs of instability. The highwalls in the Drinkwater, Mary LC and Brodie pit have actual slope angles that range between 46–48º. Scorpio Gold uses a 48º inter ramp slope for internal designs. Based on the past studies and current highwall conditions the pit deigns for reporting the Mineral Reserves were completed at a 47º inter ramp slope, with 20 ft catch benches every 40 ft. This results in a bench face angle of 66.6º. The use of preshear drillholes along the highwall has been added to the mine plan so this will also help with preserving the highwall integrity.

Production of mineralized material from both the heap and remnant pit areas has been evaluated at a nominal rate of 4,000 t/d, which results in a mine life of approximately eight years. Mining is planned on a seven day per week schedule, with two 12 hour shifts per day. The average life of mine stripping ratio is estimated to be 13.6:1 for the open pit remnant material, and 4.79:1 if the heap ore is included in the calculation.

The WRSFs (Waste Rock Storage Facility) were designed in order to minimize surface disturbance and backfill mined out pits where future mining is not anticipated.

Drill and Blast
The design parameters used to define drill and blast requirements are based on a 4.5 in blast holes on a 10 ft by 11.5 ft pattern in the mineralized zones and 6.75 in blast holes on a 13 ft by 14 ft pattern in the waste zones. Benches will be blasted and mined on 10 ft levels in the ore zones and 20 ft levels in the waste zones. The benches planned in the mineralized zones are shallower to help in controlling dilution of the ore. Buffer rows and pre-shear are planned to allow for controlled blasting and minimize damage to the highwalls. Two rotary production drills are required for initial production with up to three drills being required as production increases. A smaller track mounted drill is planned for pre-shear drilling, bedrock pioneering and drilling void patterns to collapse the old workings.

The process flowsheet developed for the Mineral Ridge heap leach residual material and open pit remnant material.

Residual material
RECLAIM AND GRINDING AREA
The grinding plant will receive residual material from the heap leaching operation. This material will be reclaimed with a front loader at a feed rate of approximately 181 t/h. The reclaimed material will be fed to a reclaim mixing tank trough a vibrating grizzly that will remove previous heap leach operation trash. The mixing tank will be agitated and process water will be added to form slurry with approximate 55% solids. The slurry will then be pumped to a holding tank (21 ft by 21 ft) with a retention capacity of 60 minutes, and then pumped to the ball mill pump box. This material will have a top size of approximately 0.25 in and a passing 80% under 0.14 in.

The slurry will feed the ball mills pump box at a controlled rate. The ball mill pump box will have approximately 90 seconds of storage capacity. The current design contemplates two ball mills (12.5 ft by 25.5 ft) with a motor of 2,400 hp each. Both mills operate in parallel with a shared pump box for both mills and in closed circuit with a cyclone pack for each mill that will control the grinding circuit product size. Pumps with variable frequency drivers will pump slurry in the pump box to the hydrocyclone packs. Each hydrocyclone pack will have nine cyclones of 10 in diameter with an arrangement of seven operating, and two in standby. The hydrocyclone overflow has a design 80% passing size (P80) of 200 mesh and will be the final grinding circuit product that will be sent to the linear trash screen in the leaching area. The hydrocyclone underflow will feed the ball mills at a circulating load of 300% and a solids content of 77% w/w. The ball mill product will report by gravity to the pump box. The mills are designed to process 2,000 t/d each net.

Open pit remnant material
A crushing facility already existing on the property will be modified to produce a final crushed transfer material to the grinding circuit of 0.39 in (10 mm) T80. In addition, an extra total power of 540 hp (270 hp each ball mill) will be necessary in the grinding circuit to accommodate the increase in the feed size from 0.14 to 0.39 in. The crushing plant will supply crushed material at a rate of 168 tph during one 12-h shift, the heap leach material will be processed during the other shift.

The crushing circuit will consist of a 32 x 48 jaw crusher (existing) with a close side setting (CSS) of 4” that will be fed by a feeder with a maximum rock size of 24 in, which is controlled through the existing grizzly. The jaw crusher product will feed a 400 hp secondary cone crusher with a CSS of 5/8 in (16 mm). The cone crusher will work on a close loop with a double deck screen (7/8 in and 5/8 in apertures) to produce a final product P80 of 3/8 in (10 mm). Final crushed product will be transported to the ball mills by a single belt conveyor, and then split to feed the two ball mills equally.

Besides the increment in power to the ball mills, all other main process equipment in the comminution and leaching circuits (cyclones, CIL tanks, thickeners, filters) will remain unchanged.

The proposed processing plant will be conventional and will re-process gold heap leach residues at a rate of 4,000 t/d. The processing plant will produce gold-loaded activated carbon from a leaching circuit. Loaded carbon will be shipped offsite for further processing. The mill feed will be supplied from the residual heap material using reclaiming methods. The tailings from the processing plant will be filtered and deposited back on the vacated area of the lined heap leach pad.

The process flowsheet developed for the Mineral Ridge heap leach residues is a combination of conventional comminution using ball mills, and CIL cyanidation to recover gold and silver. The process plant will produce gold-loaded activated carbon from the CIL circuit. The estimated gold and silver recoveries in the CIL circuit are 91% and 24% respectively for the heap leach material, and 93% and 38% for the remnant open pit material (ROM), respectively. The loaded carbon will be shippedoff-site to a re ........