Northern Vertex Announces a Preliminary Economic Assessment of the Moss Mine Gold-Silver Project, NW Arizona

Mar 28, 2013 Download PDF   Share:  Share on Facebook   Share on Twitter   Share on Google Plus   Share on LinkedIn

Pre-Tax IRR 117.9%, NPV @5% $110 Million USD, Payback Period 1.25 Years

Vancouver, BC - Northern Vertex Mining Corp. (the "Company") (TSX.V: NEE) announces the results of a preliminary economic assessment ("PEA") for its Moss Mine Gold-Silver Project, Mohave County Arizona, USA. The PEA is based on the recently announced updated resource estimate and is contained in a NI 43-101 (Disclosure Standards for Mineral Projects) compliant technical report co-authored by CDM Smith, Inc. ("CDM") and Metal Mining Consultants Inc. ("MMC") dated March 13, 2013 (the "Technical Report").

Northern Vertex has the right to earn a 70% interest in the Moss Gold-Silver Property from Patriot Gold Corp. by spending $8 million and preparing a feasibility study. The Company has spent $5.6 million to date. Subsequent to the Northern Vertex earn-in, funding of the project by the participants will be on a 70:30 proportional basis.

Preliminary Economic Assessment Highlights:

This PEA evaluates the economics of open pit mining and heap leach processing for the Moss Mine Gold-Silver Project. All figures are in USD unless otherwise stated, are based on a gold price of $1,500/oz and are on a 100% basis. Highlights are as follows:

Mine life 5 yrs, 5000 tpd, 42,000 AuEq oz/yr
Pre-tax IRR of 117.9%
Pre-tax payback of 15 months
Pre-tax NPV @5% $110 million
Capital expenditures $26.6 million
Capital / average annual oz AuEq production $633/oz
Cash Costs/oz AuEq $490/oz

Dick Whittington, President and CEO Northern Vertex Mining Corp, commented, "The results from this Preliminary Economic Assessment are positive and show the potential economics associated with the Moss Mine Gold-Silver Project. A Pilot Plant operations phase (Phase I) is recommended by the Technical Report and will precede operations (Phase II). If the Pilot Plant is successful and lab metallurgy is proven in the field, we can assess the feasibility of moving forward with operations subject to required financing. We believe that there continues to be upside in maximizing results from the in-field operations, from possible pit expansions as a result of the mine exploration programs and of course, possible Mine Life Extension or Expansion (Phase III). We look forward to advancing the project towards mine operations and to creating both shareholder value and stakeholder value in the Bullhead City Region".

Key PEA Parameters and Conclusions:

The Company's 3 Phase Mine Development Plan, as outlined in previous news releases, is designed to move the project forward from conceptual design and laboratory test work to on-site pilot plant testing (Pilot Plant - Phase I) and then onto operations (Phase II). Phase II is independent from Pilot Plant - Phase I, and will only proceed if Phase I is successful. Phase III is conceptual only, will depend on the success of Phase II, and so is not included in the PEA. Phase III would involve mine life extension and or expansion.

A summary of the key parameters and results of the PEA follow.

Operations Scope:

Pilot Plant 1 Phase I

  • Designed to in-field test the economic and technical viability of heap leach processing
  • Includes pilot-scale open pit mining and heap leach processing of an aggregate of approximately 90,000 tonnes of mineralized rock
  • All activities would be confined to patented property
  • Low strip ratio 0.79:1
  • Mined zone approximately 500 feet in length
  • Both higher grade and lower grade material will be tested in Pilot Plant - Phase I
  • Production rate of 1000 tonnes of mineralized rock / day
  • Mining and processing activities to be performed by contractors

Operations - Phase II

  • Will proceed upon determination of successful results from Pilot Plant - Phase I
  • Would include mining and processing of approximately 6.13 million tonnes (of measured and indicated resources- see below) of mineralized rock
  • Open pit mining methods and heap leach processing
  • Low strip ratio 1.6:1
  • All activities would be confined to patented property
  • Pit depth ranges from 30 feet to 575 feet
  • Production and processing activities are expected to be 5,000 tonnes of mineralized rock / day
  • Mining activities to be performed by contractors and processing activities to be performed by Northern Vertex


New National Instrument 43-101 Technical Report on Resources:

This Technical Report estimates the NI 43-101 compliant Mineral Resources at the Moss Mine Project. The updated resource estimate was prepared by Dr. Stewart D. Redwood, FIMM, and Scott Wilson of MMC and was outlined in the News Release dated March 12, 2013. The summarized resource estimate in the table below includes 12.6 million tonnes (AuEq of 1.03 g/t) of measured resources and 9.98 million tonnes (AuEq of 0.73 g/t) of indicated resources (aggregate average: 22,589,000 tonnes at 0.90 AuEq g/t) for total measured and indicated AuEq oz of 653,600 (537,000 Au oz and 5,830,000 Ag oz). It is important to note that mineral resources described herein are not mineral reserves and, as such, do not have demonstrated economic viability.

Metal Mining Consultants Inc. ("MMC") Summarized Resource Estimate
For Moss Mine Gold-Silver Project at a 0.3 g/t Au Cut-off

Resource CategoryAu Eq*(oz)Au (oz)Ag (oz)TonnesGrade
  • Gold equivalency is based on a silver:gold ratio of 50:1 and assumes 100% recovery of all metals.
  • Mineral Resources are not Mineral Reserves and do not have demonstrated economic viability. There is no certainty that all or any part of the Mineral Resources estimated will be converted into Mineral Reserves estimates.
  • Mineral resource tonnage and contained metal have been rounded to reflect the accuracy of the estimate and numbers may not add due to rounding.
  • Resources were based on 36,805 meters of drilling in 658 exploration drill holes and 530 meters of channel sampling. There were a total of 7,677- five meter composite samples used in the estimation of gold and silver. MMC used Inverse Power Distance (ID3) as the preferred estimation technique for the Moss Project.
  • MMC capped gold assays, prior to compositing 5 meter samples, at 17 grams per tonne and silver at 140 grams per tonne in order to limit the effect of high grade outlier grades in the estimation of mineral resources.
  • MMC applied Industry Standards in the selection of the drill hole and assay information gathered from historic and current exploration programs in its determination of Measured Mineral Resources, Indicated Resources and Inferred Resources.

Resource Estimates Used for Economic Assessments in the PEA:

Resources used in the economic assessment for the Moss Mine Gold-Silver Project Pilot Plant - Phase I and operations - Phase II are as follows:

Moss Mine Project Measured and Indicated Resources Estimate for Pilot Plant Operations - Phase I

Class for Phase ITonnesAu Oz EquivGrade
Au g/t
Au OzGrade
Ag g/t
Ag Oz
Pilot Plant Operations - Phase I Measured .3 - 1.0 g/t49,3011,2450.6641,0526.089,636
Pilot Plant Operations - Phase I Indicated .3 - 1.0 g/t0-0.0000-0
Pilot Plant Operations - Phase I Measured and Indicated .3 - 1.0 g/t49,3011,2450.6641,0526.089,636
Pilot Plant Operations - Phase I Measured >1.0 g/t108,0139,0912.2267,73219.5767,969
Pilot Plant Operations - Phase I Indicated >1.0 g/t14961.04655.2125
Pilot Plant Operations - Phase I Measured and Indicated > 1.0 g/t108,1629,0972.2257,73719.5567,995

*Equivalency based on 1 oz Au = 50 oz Ag

Moss Mine Project Measured and Indicated Resources Estimate for operations - Phase II

Class for Phase IITonnesAu Oz EquivGrade
Au g/t
Au OzGrade
Ag g/t
Ag Oz
Operations - Phase II Measured .3 g/t cutoff5,063,232218,4671.114181,34911.401,855,914
Operations - Phase II Indicated .3 g/t cutoff1,074,20736,6750.86329,8219.92342,670
Operations - Phase II Measured and Indicated .3 g/t cutoff6,137,439255,1421.070211,17011.142,198,584

*Equivalency based on 1 oz Au = 50 oz Ag

Moss Mine Project Inferred Resource and Waste Material Estimates for Pilot Plant Operations - Phase I and operations - Phase II

Class for Phase ITonnesAu Oz EquivGrade
Au g/t
Au OzGrade
Ag g/t
Ag Oz
Pilot Plant Operations - Phase I Inferred Resource .3 - 1.0 g/t000000
Pilot Plant Operations - Phase I Inferred Resource >1.0 g/t000000
Class for Phase IITonnesAu Oz EquivGrade
Au g/t
Au OzGrade
Ag g/t
Ag Oz
Operations - Phase II Inferred Resource .3 g/t cutoff13,1344910.93339411.534,868
Waste - Phase I and Phase II
Pilot Plant Operations - Phase I Waste3,712
Operations - Phase II Waste9,843,357

*Equivalency based on 1 oz Au = 50 oz Ag

Resource Estimates for Phase III - Mine Life Expansion / Extension:

The anticipated operating period for Phase I is 15 months and for Phase II is 5 years, including development and construction. Phase II will only proceed upon the successful completion of Phase I.

Pilot Plant - Phase I and operations - Phase II measured and indicated resources encompass 265,000 of the total 654,000 ounces gold equivalent of global resources estimated by MMC. The remaining resources (389,000 ounces gold equivalent) appear to be generally located beneath and west of operations - Phase II resources and would be available for mining at a later date. For further details on both tonnes and grade of Au and Ag separately, please see previous tables.

It should be noted that the Phase I and Phase II resources described are physically constrained to that which can be reasonably extracted by limiting mining and related facilities to patented - or private - land. The conceptual Phase III mine plan would be pursued without the physical constraint of limiting operations to patented land and will require normal course approvals from various US governmental departments and mining authorities.

Based on development of the initial resource solids containing the Phase I and Phase II resource, the mining extraction recovery rate of the in-situ resource is anticipated to be 100 percent.

As mentioned above, upon the completion of Phase II, 389,000 oz AuEq will remain. Extending mining and processing operations onto unpatented land by mining along strike and to depth has the potential to extend the life of the mine. This will be the subject of further investigation concurrent with Phase II operations. This investigation will incorporate permitting, technical, economic, and financial elements into one or more pre-feasibility and/or feasibility studies.


Overall metallurgical data shows that ore from the Moss Mine Gold-Silver Project is readily amenable to agglomeration - heap leach cyanidation processing. Column test recoveries obtained from the bulk samples, finely crushed using rolls crushers and agglomerated using cement as a binder, ranged from 75% to 84.6% for gold and from 61.3% to 76.6% for silver. Recovery percentages are summarized in the table below:

McClelland Leach Test Recovery Results

TestFeed SizeAu Recovery (%)Ag Recovery (%)
1X Rolls HG CompositeP85-1/4”7569
1X Rolls HG Column TestP85-1/4”75.361.3
2X Rolls HG CompositeP95-1/4”8476
2X Rolls HG Column TestP95-1/4”84.676.6

Gold extraction was still progressing when column leach tests were terminated for purposes of completing the PEA and is expected to increase further with a longer leach cycle. Preliminary data from an ongoing column leach test indicate that the low grade mineralization will be amenable to agglomeration/heap leach cyanidation processing after rolls crushing to a 95%-1/4" feed size. Use of industrial scale high pressure grinding rolls (HPGR) has the potential to improve liberation and yield higher recoveries.

The favorable results from the labatory metallurgical testing provide the basis for proceeding with the proposed field testing Pilot Plant - Phase I. Metallurgical data from the Pilot Plant program will be collected and analyzed for use in the design of operations - Phase II. Both higher grade and lower grade mineralized rock is expected to be tested in the Pilot Plant. Although positive results have been obtained to date, additional metallurgical test work will be required. Consequently, recoveries used in the PEA have been scaled back to 75% for Au and to 55% for Ag.


The Preliminary Economic Assessment recommends a continued exploration program to further delineate the mineralization at the Moss Gold-Silver Project. The limits of mineralization are still open at depth and to the west. The recommended drilling program includes additional drilling of 2,200 meters and associated costs are outlined in the table below:

Estimated Costs for Continued Exploration and Drilling Program

Core Studies$10,000

Production and Economic Criteria:

The key Production and Economic Criteria outlined in the PEA are as follows:

Project ElementPhase II (1)
Resource (6)
M&I Resource (tonnes)6,137,439
M&I Resource (gram Au/tonne)1.07
M&I Resource (gram Ag/tonne)11.14
M&I Silver : Gold ratio10.4:1
M&I Resource (AuEq oz)(2)255,100
Strip Ratio (waste/resource)(1) (5)1.6:1
Mine Life (years) (7)5
Tonnes / day (nominal)5,000
Total tonnes processed6,218,036
Gold Recovery (%)75%
Silver Recovery (%)55%
Total oz. Recovered (Au)145,465
Total oz. Recovered (Ag)1,107,516
Total oz. Recovered (AuEq)(2)167,616
Average Annual Production oz AuEq42,000
Cost / tonne$13.25
Financial (6)
Estimated Capital (US $)$26,618,000
Capital / Total Recovered AuEq oz (US $/oz)(2)$158
Capital / Avg Annual Production AuEq oz$633
Cash Cost / Recovered AuEq oz (US $/oz)(2)(4)$490
Net Present Value (NPV), 5%(3)$109,762,415
Discounted Cash Flow Rate of Return (DCF/ROR)(3)117.9%
Payback Period (years)(3)1.25

(1) Will only proceed if Phase I is successful
(2) Equivalency based on 1 oz Au = 50 oz Ag
(3) NPV, DCF/ROR, and payback are calculated based on $1500/oz. Au on a pre-tax and pre-royalty basis
(4) Operations and Maintenance (O&M) costs (includes G+A)
(5) Excludes stockpiled mineralized rock
(6) The reader is cautioned that mineral resources described herein are not mineral reserves, and, as such, do not have demonstrated economic viability
(7) Mine life for operations - Phase II is based on mineable resources on patented land only and has not been established using economic cut-off criteria.

Sensitivity Analysis:

The following table shows the variances to the Net Present Value (NPV) and Internal Rate of Return (IRR) from the base case of $1500 gold and $30/oz silver.

PricesIRRNPV @5%
Gold $1300/oz
Silver $26/oz
88%$82 million
Gold $1500/oz
Silver $30/oz
117.9%$110 million
Gold $1700/oz
Silver $34/oz
150%$137 million

Various other sensitivities have been carried out assessing the effects of:

  • An increase in capital cost by $10 million
  • An increase in operating costs by 20%
  • An increase in gold and silver recovery rates to match higher recovery rates in lab results
  • An increase in costs of diesel fuel for power production by $1 per gallon
  • A decrease in capital equipment costs by 25% by way of using used equipment instead of new
  • An increase in pit slope from 55 degrees to 65 degrees
  • A decrease in delay of NSR receipts from 25% to 10%

The results are attached as Appendix 1 and indicate the robust nature of the Moss Mine Gold-Silver Project.

About Northern Vertex:

Northern Vertex Mining Corp. is a Canadian based exploration and mining company focused on the reactivation of the Moss Mine Gold-Silver Project located in NW Arizona, USA. The Company has an experienced management team with a strong background in all aspects of acquisition, exploration, development, operations and financing of mining projects worldwide. The Moss Mine Gold-Silver Project is a potential heap leach, open pit project being advanced under a three phase business plan, specifically designed to ensure that technical, economic, permitting and funding requirements are met prior to each phase proceeding. The Company is focused on working effectively and respectfully with our stakeholders in the vicinity of the historical Moss Mine and enhancing the capacity of the local communities in the area.

Qualified Persons:

The Technical Report and Preliminary Economic Assessment for the Moss Mine Gold-Silver Project was prepared by CDM Smith, Inc. and Metal Mining Consultants, Inc. and incorporates the work of a number of industry consultants all of which are Qualified Persons (as defined by National Instrument 43-101) who are independent of Northern Vertex Mining Corp. Each of the consultants has reviewed and approved this news release. A list of the Qualified Persons associated with the above Technical Report and Preliminary Economic Assessment are shown in the table below.

Qualified Person
Scott Wilson, CPG
Stewart Redwood, FIMM
Brian Antonioli, PE
John Gormley, PE, Ph D
John Brower, CPG, Ph D
Jack McPartland, CPG, Ph D

The foregoing technical information contained in this news release has also been reviewed and verified by Mr. Colin McKenzie, General Manager of Exploration for Northern Vertex and a Qualified Person ("QP") for the purpose of National Instrument 43-101 (Disclosure Standards for Mineral Projects).


J.R.H. (Dick) Whittington, President & CEO

For further information, please visit
or contact Investor Relations at: 604-601-3656 or 1-855-633-8798

Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.

Cautionary Note About Forward Looking Information
This news release contains statements about our future business and planned activities. These are "forward-looking" because we have used what we know and expect today to make a statement about the future. Forward-looking statements including but are not limited to comments regarding the timing and content of upcoming work and analyses. Forward-looking statements usually include words such as may, intend, plan, expect, anticipate, believe or other similar words. We believe the expectations reflected in these forward-looking statements are reasonable. However, actual events and results could be substantially different because of the risks and uncertainties associated with our business or events that happen after the date of this news release. You should not place undue reliance on forward-looking statements. As a general policy, we do not update forward-looking statements except as required by securities laws and regulations

Cautionary Note to U.S. Investors:
This news release uses the terms "Measured", "Indicated", and "Inferred" resources. U.S. investors are advised that while such terms are recognized and required by Canadian regulations, the United States Securities and Exchange Commission does not recognize them. "Inferred Mineral Resources" have a great amount of uncertainty as to their existence, and as to their economic and legal feasibility. It cannot be assumed that all or any part of an Inferred Mineral Resource will ever be upgraded to a higher category. Under Canadian rules, estimates of Inferred Mineral Resources may not form the basis of feasibility or other economic studies. U.S. investors are cautioned not to assume that all or any part of Measured or Indicated Mineral Resources will ever be converted into Mineral Reserves. U.S. Investors are also cautioned not to assume that all or any part of a Mineral Resource is economically or legally mineable.

2013 number 07

Appendix 1

Sensitivity Economics for operations - Phase II (Pre-Tax):

Cost ComponentVariationDCF/RORNPV, 5%
Base Case: Gold = $1500/oz;
Base Case: Silver = $30/oz)
Table 3: Increase in gold and silver pricesGold = $1700/oz
Silver = $34/oz
Table 4: Decrease in gold and silver pricesGold = $1300/oz
Silver = $26/oz
Table 5: Increase in capital costIncrease = $10,000,00082.2%$101
Table 6: Increase in Cash (O&M) costIncrease = 20%97.3%$96
Table 7: Increase in gold and silver recoveryGold recovery = 84.6%;
Silver Recovery = 76.6%
Table 8: Increase in diesel priceDiesel increase by $1/gallon to $4.75/gallon
Electrical cost increase to $3.622/tonne
Table 9: Used equipment option: generators, heavy equipment, crushing plant, and conveyor systems rather than new equipment (base case)Decrease = 25%
Decrease capital cost = $3,300,000
Table 10: Increase in pit slope from average 55 degrees to average 65 degreesDecrease in strip ratio to 1.25:1
Decrease in waste rock cost by $3.3 million
Increase in recovered gold equivalent by about 4,600 oz. due to wider pit or $7 million
Increase in slope rock bolting by $7.6 million
Table 11: Decrease in delay of NSR receiptsDecrease to 10% from 25% the amount of revenue delayed until following year142.4%$111

(1) Table number corresponds to tables contained in Appendix L.