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United Silver Corp. Releases Positive Preliminary Economic Assessment and Reports Updated Estimated Resources

29.07.2013  |  Business Wire

United Silver Corp.:

-- PEA Mineralized Tons Processed (Diluted)


601,000 Tons

-- Silver Recovered

6,108,000 Ounces

-- IRR at $20 US Silver

31% Post Tax

-- Net Present Value @ 8% Discount


-- Cash Cost Per Ton Mill Feed Mined

$99.93 Per Ton

-- Cash Cost Per Ounce Recovered

$9.83 Per Oz Silver

-- Preproduction Development Cost


-- Total Capital Cost


United Silver Corp. (“United Silver Corp.”, the “Company:, or “USC”: TSX; USC: OTC; USCZF: Frankfurt: UM8) announces the results of an updated National Instrument (“NI”) 43-101 compliant resource estimate and Preliminary Economic Assessment (“PEA”) for its Crescent Mine located in the Big Creek drainage of Shoshone County in the Silver Valley of North Idaho, United States of America (“USA”). This NI 43-101 Technical Report which was independently prepared by SRK Consulting (U.S.) Inc. (“SRK”) of Reno, Nevada, USA, determined that USC’s Crescent Project silver deposits demonstrate strong economics at the PEA level. The updated resource estimate indicates the in situ Measured and Indicated resources increased 8.7% and the Inferred resources increased 28.4% on an ounces basis at a silver cut-off grade of 8 ounces per short ton (“opt”) as compared with the resources in the SRK NI-43-101 Technical Report filed on SEDAR May 31, 2010. The 2013 resource estimate is informed by a larger drill database and the addition of over 2,300 ft of production data from recent development drifting. USC also provided a more extensive database of density determinations, which resulted in an increase in the average density for the deposit.

SRK concludes that the property merits the expenditure of additional funds to complete the secondary egress, the completion of additional development drifts on structure to further define and delineate the three mineralized veins identified to date, implementation of diamond drilling to assist with further resource delineation within the three veins, exploration drifting on structure to explore mineralized veins along strike and additional metallurgical test work to try and enhance the recoveries achieved to date on 12,607 tons of mineralized material mined from development and exploration headings.

The 2013 updated Mineral Resource was prepared by SRK’s Jay Pennington, C.P.G. with 28 years of exploration and resource geology experience in precious and base metals and a qualified person (“QP”) with respect to Mineral Resource estimation under NI 43-101. Table 1 reports the total in situ underground Mineral Resource at a cut-off grade of 8 opt.

Table 1 – Mineral Resource Statement for the Crescent Silver Deposit, SRK Consulting (U.S.) Inc., July 22, 2013



opt Ag




Grade opt


Mozs Ag


South Vein

& Indicated

8 opt 236,000 14.4 3.4

Alhambra Vein

& Indicated

8 opt 152,000 13.2 2.0

Jackson Vein

& Indicated

8 opt 132,000 15.9 2.1

Total Measured &

  8 opt   520,000   14.4   7.5
South Vein Inferred 8 opt 152,000 18.4 2.8


Inferred 8 opt 118,000 10.2 1.2


Inferred 8 opt 260,000 17.7 4.6
Total Inferred   8 opt   530,000   16.2   8.6


1. Mineral resources that are not mineral reserves do not have demonstrated economic viability.
2. No measured or indicated mineral reserves have been defined.
3. The cut-off grade for mineralized zone interpretation was 4 opt.
4. The block cut-off grade for defining Mineral Resources was 8 opt.
5. The silver price used was $US 20 per troy ounce, mining and processing costs of $99.93/ore ton, and 92% mill recovery were used to define the 8 opt cutoff.
6. The resources reported above are non-diluted.
7. Measured Resources required blocks to be informed by a minimum of 8 composites and those blocks must be less than 120 ft from previous production.
8. Indicated Resources required blocks to be informed by composites from a minimum of two drill holes and distance from data less than 300 ft
9. The resources mined from the intermediate drifts have been deleted from the 2013 updated resources.

No measured or indicated reserves of any category were identified. Although a conceptual Preliminary Economic Assessment (PEA) was completed, no formal economic or engineering work that would enable identification of mineral reserves has yet been carried out. Mineral resources are not mineral reserves and by definition do not demonstrate economic viability. There is no certainty that all or any part of the mineral resources will be converted into mineral reserves.

Due to the uncertainty that may be attached to Inferred Mineral Resources, it cannot be assumed that all or any part of an Inferred Mineral Resource will be upgraded to an Indicated or Measured Mineral Resource as a result of continued exploration. Confidence in the estimate is insufficient to allow the meaningful application of technical and economic parameters or to enable an evaluation of economic viability worthy of public disclosure. Inferred Mineral Resources are excluded from estimates forming the basis of feasibility or pre-feasibility studies.

The updated resource estimate was informed by 279 drill holes and 1,357 chip channel assays from three intermediate drifts completed on the South Vein and one intermediate drift on the Alhambra Vein that were completed since the 2010 resource update was filed. Estimation was carried out using inverse distance weighting of declustered full-vein-width composites. Independent vein wireframes were used to code block percents into model blocks with dimensions 25x25x50 ft (XYZ, respectively).

The Technical Report identifies, estimates and summarizes resources in the three veins incorporated in this updated resource estimate. The three veins are the Alhambra Vein which prior to 2011 has produced over 25 million ounces at an average grade of 27 opt silver. The South Vein, a structure whose existence has been known for more than 50 years, but was not known to host potential economic grade mineralization until surface drilling intercepts identified that mineralization in 2007. The Jackson Vein, a newly identified vein that was not distinguished from the South Vein during the 2007 through 2010 drilling campaigns. This vein was modeled as a separate vein during the updated resource estimate based on mapping and assay data obtained from three of the intermediate drifts completed during underground exploration and development work in 2011 and 2012. There is a strong indication that the Jackson Vein may be a link vein between the South Vein and the Alhambra Vein which generates a new and focused exploration target for future diamond drilling and underground development.

The deposit model identified strike and dip extensive zones of mineralization on both of the narrow vein structures hosting the Alhambra (2,000 feet on strike and 2,000 feet down-dip) and South Veins (2,000 ft on strike and 1,800 feet down-dip). The Jackson Vein was identified over a smaller area (1,400 ft on strike and 1,500 ft down-dip). Mineralization averages 3.5 feet wide on the South Vein but varies from less than 1 foot to 18 feet wide. The Alhambra Vein averages 3.0 ft wide and varies from less than 1 foot to 10 ft wide. The Jackson Vein averages 2.5 ft wide and varies from less than 1 foot to 5 ft wide. Silver mineralization in all three of these veins is hosted in St Regis rocks, a lithologic rock unit known to be a favorable host for high grade silver mineralization in other mines along the Silver Belt.

Crescent Mine Resources

In this NI 43-101 resource update, SRK lowered the block model cut-off grade from 11 opt to 8 opt and used a silver price of $20 per ounce. The lower cutoff grade is supported by recent collaborative mine planning and cost estimation carried out by USC and SRK.

The Mineral Resource used as the basis for the PEA is presented in Table 2.

Table 2 – Summary of PEA Mineral Resources by Resource Category



  Cut-off   Tons  






opt Ag (Undiluted)

opt Ag

Mozs Ag

South Vein

& Indicated

8 opt 169,000 15.4 2.6
Alhambra Vein

& Indicated

8 opt 104,000 13.5 1.4
Jackson Vein

& Indicated

8 opt 44,000 18.2 0.8

Total Measured &

  8 opt   317,000   15.1   4.8
South Vein Inferred 8 opt 71,000 16.2 1.2

Alhambra Vein

Inferred 8 opt 43,000 10.7 0.5

Jackson Vein

Inferred 8 opt 20,000 12.5 0.3
Total Inferred   8 opt   134,000   13.9   1.9

CEO Graham Clarke of United Silver Corp. commented “USC continues to deliver on its plan to return the Crescent Property to commercial production and profitable mining operations. This NI 43-101 resource update confirms the presence of three veins that host silver mineralization averaging from 12.6 to 15.9 opt using a cutoff grade of 8 opt. The material considered for mine planning and the PEA economic evaluation consists of a Measured and Indicated Resource of 317,000 tons containing 4.8 million ounces at an average grade of 15.1 opt silver and an Inferred Resource of 134,000 tons containing 1.9 million ounces of silver at an average grade of 13.9 opt.”. “The PEA economic model indicates that when using a silver price of $20 per ounce, the Project has an IRR of 31% and an NPV of $8.8 million using an 8% discount rate. Additionally, block modeling has identified large target areas for exploration between widely spaced drill holes (from 200 to more than 500 feet) that will be explored and developed using both underground mine development and diamond drilling The exploration program is designed to increase both the quantity and quality of resources as development drifting is completed. As soon as additional financing is completed USC will begin implementing SRK’s recommendations.”

Highlights of the Preliminary Economic Assessment at $20 per ounce silver

SRK’s NI 43-101 compliant Technical Report contains a PEA of the Crescent Mine Project, which means the report is a preliminary assessment study that includes an economic analysis of the potential viability of mineral resources developed at this early stage of the Project. While a typical PEA is accurate to +/- 35% , the Crescent PEA cost estimation is considered by SRK to be of higher confidence, and was developed from a combination of actual costs from recent underground development work and first principals consisting of best available estimates from mine/mill cost and designs in conjunction with the NI 43-101 updated resource estimate. Because a PEA is not a feasibility or formal economic study, inferred resources were utilized in the assessment. It was completed in support of the NI 43-101 resource update.

Previous underground development work produced slightly more than 12,607 tons of material that was milled at the New Jersey Mining Company (“NJMC”) mill. Milling costs and silver recovery were based on costs and results from that work. Smelting and refining charges are based on actual costs for the concentrates produced.

Table 3 – Operating parameters utilized

Mining Costs

  $55.09 per ton
Processing Cost (Including haulage, mine to mill) $26.76 per ton
General and Administrative $18.08 per ton
Total Costs $99.93 per ton
Dilution 33%
Mill Recovery 92%
Production Rate 400 tons per day
Mining Schedule 7 days per week
Silver Price $20 per ounce
Cost Per Once Produced $9.83 per ounce

Preproduction development costs include mine development capital with a 25% contingency, costs for test mining, exploration drilling and initial working capital. These costs will be offset by $1,856,000 income from processing of mineralized material produced from test mining.

The mine plan is based on a 34 week mine development schedule to tie the upper Countess Decline to the lower Big Creek #4 Cross Cut. Normal mine production will begin as soon as these headings intersect, enabling a second means of egress from the mine. During this period there will also be some additional development from the Countess Decline to access the South Vein for stope development on additional mining levels.

Production is scheduled from the South, Jackson and Alhambra Veins. The South and Jackson Veins will use a mechanized mining system incorporating primarily uncemented waste rock for backfill. The plan allows for the mineralized material to be blasted first and removed from the stope. Waste will then be blasted and left in the stope for backfill and to make sufficient room for mechanized equipment to work in the stope. A one foot cemented backfill cap will be placed on the backfill to minimize loss of mineralized material into the fill. One foot of dilution at zero grade has been incorporated into the schedule and economics. It is expected that Jackson Vein mining will be similar to that for the South Vein.

The Alhambra Vein will be mined using a conventional overhand cut and fill stoping method. Each stope will incorporate two manways into the stope to allow for ventilation and alternate egress and an ore chute. The blasting and moving of mineralized material will be similar to the South Vein with allowances for the narrower vein expected along the Alhambra Vein. Mineralized material will be moved to the chute using slushers. LHDs will haul the material from the chutes to the ore pass where it will fall to the Big Creek #4 level and be hauled in rail cars to the surface.

Opportunities and Recommendations

The Project is very sensitive to silver prices; a decrease in the silver price to $18/oz lowers the IRR to 5%. Increasing the silver price to $22 raises the IRR to 55%. Each $1.00 increase in the price of silver will improve the IRR approximately 12.5%.

SRK recommends diamond drilling from current underground workings to increase the confidence in the mineralized grade and thickness of under-explored areas of the current resource that are included in the mine plan.

Additional exploration drilling and drifting is recommended following completion of the secondary exit to resume exploring underexplored areas along the strike lengths of both the Alhambra and South Vein structures. With the presence of the Jackson Vein as a possible link vein between the Alhambra and South Vein, exploration should be conducted for additional link veins.

Additional metallurgical testing is recommended to improve silver recovery in oxidized portions of veins, primarily those areas within about 500 feet of the surface. Testing is also recommended to determine how to improve concentrate grades. USC also plans to investigate other smelter alternatives to achieve more favorable smelter terms.

The technical aspects of this press release have been reviewed and approved by Michael P. Gross M.S., P.Geol., Chief Operating Officer of United Silver Corp., who is the “Qualified Person” for this project as defined by NI 43-101 regulations.


USC is a vertically integrated Canadian mining company with operations in Idaho, USA. It has an 80% interest in the Crescent Silver Mine project in the Silver Valley’s prolific Silver Belt - directly between two of the district’s historically largest silver producing properties, the Sunshine and Bunker Hill mines. USC also offers a full suite of mining services including contract mining and providing a complete fabrication shop and service for building and repairing mining equipment to silver miners in the district. USC's common shares trade on the Toronto Stock Exchange under the symbol "USC". For more information about USC, please visit:


Graham Clark
Chief Executive Officer

For further information, please contact
Graham Clark

The TSX has not reviewed and does not accept responsibility for the adequacy or accuracy of the content of this news release.

Forward-Looking Statements

This news release contains forward-looking information which is subject to a variety of risks and uncertainties and other factors that could cause actual events or results to differ from those projected in the forward-looking statements. Forward looking statements in this press release include that USC continues to deliver on its plan to return the Crescent Property to commercial production and profitable mining operations; that large target areas for exploration between widely spaced drill holes that will be explored and developed; that the exploration program can increase both the quantity and quality of resources as development drifting is completed; that the program will be carried out as indicated; and that as soon as additional financing is completed USC will begin implementing SRK’s recommendations. These forward-looking statements are based on the opinions and estimates of management and its consultants at the date the information is disseminated. They are subject to a variety of risks and uncertainties and other factors that could cause actual events or results to differ materially from those projected in the forward-looking information. Risks that could change or prevent these statements from coming to fruition include changing costs for mining and processing and their impact on the cut off value established; increased capital costs; changing forecasts of mine production rates; the timing and content of upcoming work programs; geological interpretations based on drilling that may change with more detailed information; potential process methods and mineral recoveries assumption based on limited test work and by comparison to what are considered analogous deposits that with further test work may not be comparable; the availability of labour, equipment and markets for the products produced; market pricing for the products produced; our possible inability to service our debts and pay liabilities as they become due; and despite the current expected viability of the project, conditions changing such that the minerals on our property cannot be economically mined, or that the required permits to build and operate the envisaged mine can be obtained. The forward-looking information contained herein is given as of the date hereof and the Company assumes no responsibility to update or revise such information to reflect new events or circumstances, except as required by law.


United Silver Corp.
Graham Clark, 604-696-4236
Chief Executive Officer

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