Introduction
The Mineral Ridge project, a former producer, is located ~6 km northwest of the town of Silver Peak and 51 km west of Tonopah in Esmeralda County, Nevada. The property consists of 351 mining claims totalling 4,118 hectares (10,176 acres).
Mineral Ridge has historically produced almost 575,000 ounces of gold, including ~170,000 ounces from open pit and ~405,000 ounces from underground mining operations. The operation has a well constructed and upgraded infrastructure including roadways, power grid and station, heap leach pad, crushing circuit, gold adsorption-desorption-recovery ("ADR") plant, water supply, maintenance shop, refuelling and storage facility, administration buildings and rolling load-haul-dump ("LHD") equipment.
The property is currently bonded and permitted for heap leach gold processing and production. The dry climate and non-acid generating character of the rock offers favourable conditions for mining and reclamation operations.
Scorpio Gold holds a 70% interest in the Mineral Ridge gold project in a joint venture agreement with Golden Phoenix Minerals Inc. (30%), and can acquire up to a 100% interest in the project, subject to terms and conditions as outlined in the Company's January 5, 2010 news release and subsequent amendments noted in the Company's August 5, 2011 news release. Scorpio Gold is assigned the right and initial responsibility to fund, manage and operate the project.
Current Operations
Scorpio Gold has completed all of the major site rehabilitation to bring the Mineral Ridge project to a fully operational status, including:
- Replacement of carbon columns in the ADR gold recovery plant and rehabilitation of the loaded carbon handling equipment.
- Removal of gold-bearing sludge from the barren pond and liner repairs made to the pregnant/barren ponds.
- Installation of a new fuel storage facility with concrete pads and double walled storage tanks to prevent spillage.
- Building expansion and installment of new equipment in the on-site assay laboratory.
- Purchase of a portable crushing unit rated at 600 tons per hour.
The crushing of the gold-bearing material mined by previous owners was completed in February 2011 with some 280,000 tons placed on the leach pad. The heap leaching process was initiated in late in February with the application of the leaching solution.
Scorpio Gold engaged mining contractor, Ledcor CMI Inc., Ledcor to perform all aspects of drilling, blasting, loading and hauling of material. The first pre-production blast took place in the Drinkwater pit on May 31, 2011. Processing of mineralized material from the Drinkwater pit began in early June and production through the end of September stands at 215,322 dry tons.
Gold and silver bearing solution from the leach pad is collected in the pregnant pond and processed through carbon columns in the ADR plant for recovery of the precious metals from leachate on carbon. As the concentration levels of precious metals increase, the loaded carbon is transferred from the carbon columns into storage bags and prepared for shipment to Metals Research in Kimberley, Idaho for processing into doré. The doré bars are then delivered to Johnson Matthey's refinery in Salt Lake City for further refining of the precious metals into separate 99.9% pure gold and silver bars.
The first shipment of loaded precious metals carbon left site on April 18, 2011 and is now shipped on a bi-weekly basis. On June 23, 2011, Scorpio Gold made its first precious metals sale, with 623 ounces of gold and 301 ounces of silver sold to Waterton Global Resource Management, as per its sales agreement. As of September 30, 2011, 61 tons of loaded carbon containing an estimated 5,933 ounces of gold and 3,172 ounces of silver have been shipped to Metals Research. During the third quarter, the Company's metal sales from its production of recovered gold and silver totalled 2,399 ounces of gold and 1,999 ounces of silver.
In November 2011, the Company commenced pre-stripping of the Mary Zone in preparation for commencement of open pit mining. The Mary Zone is located immediately southwest of the Drinkwater Pit where mining is currently in progress. A 58 hole drill program to define the extent of mineralization for final pit design is underway. Mining of the Mary Zone is expected to commence later in January 2012, adding to current production from the Drinkwater Pit and increasing the overall production at Mineral Ridge.
The Company continues to update the drill hole database in preparation for a NI 43-101 compliant mineral reserve and resource estimate and feasibility study by AMEC with estimated completion in Q1 2012. This study will incorporate actual costs and parameters of the current operation.
Exploration
The Company is engaged in an aggressive three-phase drill program budgeted at 13,000 m for 2011. Phase I drilling is designed to expand and upgrade the existing mineral resource estimate in the vicinity of the existing pits scheduled for mining in 2011. Phase II is designed to further expand the resource base and define additional open pits. Phase III is focused on a property-wide exploration scale to target numerous gold-bearing mineralized zones/structures discovered during the Company's surface exploration program.
Initial results from the Phase I drilling continue to successfully expand the known mineralization beyond the existing open pit areas (see
April 12, 2011 news release).
Coyote Target
The Coyote target is located approximately four km southwest of the Mineral Ridge operation and on strike with the Brodie mineralized body, which lies adjacent to the heap leach pad.
Surface exploration in the Coyote target area has outlined a 1.0 km long, north-northeast trending structural corridor that ranges from 200 m in width in the south to 300 m in the north and is open in all directions. Structural features of the corridor are traceable on surface a further three km northeast to the Mineral Ridge operation; however, detailed surface prospecting and sampling has yet to be conducted over this extent due to the rugged terrain.
Numerous historical workings (circa 1900's) lie within the area, including seven shallow shafts, one adit and six trenches. Surface grab sampling has reported values up to 14 grams per tonne (0.5 ounces per ton) gold.
First pass drilling of the Coyote target has resulted in the discovery of widespread silver-enriched mineralization over significant widths. Eleven holes tested the target over a 250 x 600 metre area, while 2 holes tested an outlier zone located 914 metres to the northwest (see
September 13, 2011 news release).
The extensive and thick silver-mineralized zone appears to have overprinted earlier gold mineralization, and is presently thought to be wedge-shaped and thickening to the northwest. All of the holes in this first ever drilling of the Coyote target terminated in mineralization. Mapping and geochemical sampling is underway to determine the surface expression and relevance of this discovery to other mineralization on the property. The widespread nature of mineralization crossing various lithological host units may be indicative of a very large mineralized system.
Solberry and Brodie Deposits
First phase drilling at the satellite Solberry and Brodie deposits has returned high-grade intersections as presented in the Company's
September 26, 2011 and
October 18, 2011 news releases, respectively.
Follow-up drilling on the Brodie Zone (see
November 15, 2011 news release ) targeted its northwest extension and has now defined a mineralized trend over an 850 metre (2,800 foot) strike length, remaining open in both northwest and southeast directions. The trend is on strike with the Bluelite Zone located 1,370 metres (4,500 feet) to the northwest.
Wedge Deposit
The Wedge deposit is located 225 metres west of the Drinkwater pit where the Company is currently mining. Initial drilling has intersected near surface mineralization as presented in the Company's
November 8, 2011 news release. Given the shallow depth of the mineralization and its close proximity to the crushing unit and haul roads, the Company is examining the viability of adding the extraction of this zone into the 2012 mine planning. This addition has the potential to increase the overall gold production scheduled for the coming year
Geology & Mineralization
The Mineral Ridge gold deposits are located on the northeast flank of the Silver Peak Mountain Range. This range lies in the southern reaches of the Great Basin, within the Walker Lane structural corridor. The Walker Lane is a 100-km-wide region of right lateral, wrench-faulting which separates the Sierra Nevada batholith to the west and southwest and the Great Basin to the east and northeast.
Mineral Ridge is an anticlinal dome found on the eastern flank of the Silver Peak Range. It has been interpreted as an uplifted metamorphic core complex where unmetamorphosed and unfolded Cambrian strata are in detachment-fault contact with underlying deformed granitoids and Precambrian metamorphic rocks of the core complex. Auriferous quartz lenses of the central gold-quartz district are concordant with foliation in the Precambrian Wyman Formation host rock. Transitional contacts were observed between quartz and alaskite (commonly pegmatitic), and between alaskite and peraluminous two-mica granite, strongly suggesting that the alaskite, quartz, and ore metals were derived hydrothermally from residual granite melt and aqueous fluids.
The property is located on a typical "Nevada Structural System" which is known to control gold mineralization.
To date, seven well-defined gold bearing structures have been documented on the property as follows:
- The North-Northeast Eagles Nest Fault
- The North-Northeast Coyote Fault
- The Northwest BW Normal Fault
- The North-Northwest Gillian Fault
- The Northeast Mary/Drinkwater Cross Fault
- The North-Northwest Mary/Drinkwater Cross Fault
- The North-Northwest Black Warrior Intersection Fault
The known mineralized zones occur over an area of approximately 4,300 m (14,000 ft) north-south and 4,600 m (15,000 ft) east-west. Individual zones can be as much as 43 m (140 ft) thick, usually consisting of a higher-grade 1.5- to 9.0-m wide halo surrounded by a lower-grade mineralized envelope. Two or more high-grade zones are commonly observed stacked on one another. Gold deposition is structurally controlled, and some of the highest grade material is found in mineralization shoots that are at an oblique angle to the direction of movement of the upper plate slab.
Gold is present as native gold and electrum, and generally occurs as rounded, angular, irregularly shaped and elongated inclusions and intergrowths in quartz, frequently associated with micaceous minerals or carbonates occupying interspatial spaces or fracture filling. Gold is also frequently associated with goethite, sometimes with relict pyrite and on occasions intergrown with sphalerite, galena, anglesite/cerrusite and pyrite.
The Company has completed a property-wide, multi-spectral satellite imagery survey, including alteration mapping, detailed elevation mapping and lithological enhancement. The resulting data sets and image maps will greatly enhance geological and structural interpretation, and are being integrated into the existing database to help detect similar types of mineralized settings on the property.
Deposits
Over 94,000 m (310,000 ft) of historical drilling resulted in the delineation of eight exploitation pits and an additional three potential pits. The Drinkwater and Mary are two main deposits included in the initial mineral resource estimate by Scorpio Gold. Resource estimates have yet to be conducted on the satellite Wedge, Brodie and Solberry-Bluelite deposits.
Drinkwater Deposit
The Drinkwater Deposit is the largest known mineral deposit and is located on the northeastern side of the metamorphic and intrusive core complex. It was partially mined by underground methods from the 1860s to the early 1940s and by open pit methods from 1989 to 1999. The mineralized zones in the Drinkwater deposit have a general strike of N45W and dips about 20 to 25 degrees to the northeast. Drilled defined mineralized zones have a strike length of over 750 m (2,500 ft), down dip extension of over 600 m (2,000 ft), two or more gold bearing shear zones with an individual thickness of 1.5 to 12 m (5 to 40 ft) and an overall thickness of more than 30 m (100 ft).
Mary Deposit
The drilled defined mineralized zones have a strike length of over 600 m (2,000 ft), down dip extension of over 450 m (1,500 ft), with mineralized zones generally thinner and less continuous but higher in grade than those in Drinkwater.
Wedge, Brodie and Solberry/Bluelite Deposits
These satellite deposits host multiple horizontal mineralized bodies and are all open for expansion. Further drilling is required prior to the preparation of mineral resource estimates.
Mineral Resource Estimate
On June 21, 2010, Scorpio Gold announced the first ever NI 43-101 compliant mineral resource estimate on the Mineral Ridge gold deposit, as audited and compiled by Micon International Limited ('Micon') of Toronto, Ontario. The estimate has outlined a total of 221,000 ounces of gold in the measured and indicated categories and 136,000 ounces of gold in the inferred category within the area of the Drinkwater and Mary pits.
Table 1. Summary of Measured, Indicated and Inferred Resources - Drinkwater and Mary Deposits
| Deposit |
Category |
Tons |
Tonnes |
Au (OPT) |
Au (g/t) |
Au (oz) |
| Drinkwater |
Measured |
239,000 |
216,817 |
0.066 |
2.263 |
16,000 |
|
Indicated |
3,009,000 |
2,729,719 |
0.043 |
1.474 |
129,000 |
|
Measured & Indicated |
3,248,000 |
2,946,536 |
0.045 |
1.543 |
145,000 |
|
Inferred |
2,190,000 |
1,986,735 |
0.031 |
1.063 |
69,000 |
| Mary |
Indicated |
1,449,000 |
1,314,511 |
0.052 |
1.783 |
76,000 |
|
Inferred |
1,603,000 |
1,454,217 |
0.042 |
1.440 |
67,000 |
| Total Drinkwater & Mary |
Measured & Indicated |
4,697,000 |
4,261,047 |
0.047 |
1.61 |
221,000 |
| Total Drinkwater & Mary |
Inferred |
3,793,000 |
3,440,952 |
0.036 |
1.234 |
136,000 |
Note 1: Cut-off grade = 0.01 OPT Au.
Note 2: This mineral resource estimate includes technical information which requires subsequent estimates to derive sub-totals, totals and weighted averages. Such estimations inherently involve a degree of rounding and consequently introduce a margin of error. Where these occur, Micon does not consider them to be material.
Note 3: The effective date of the mineral resource estimate presented above is May 31, 2010.
Note 4: Mineral resources that are not mineral reserves do not have demonstrated economic viability. There are no mineral reserves presently identified on the Mineral Ridge Property.
A summary of the parameters incorporated for the preparation of this estimate is presented in the Company's June 21, 2010 news release. The estimate, as audited and compiled by qualified persons Charley Murahwi, P.Geo. and Alan J. San Martin, AusIMM of Micon, was prepared using drilling data available up to February 28, 2010. Further details regarding the methodology used for the mineral resource estimate are presented in the NI 43-101 compliant technical report filed on SEDAR and available in the Technical Reports section below.
Technical Reports