Orvana Minerals Corp.

Orvana Minerals Corp.

March 22, 2010 10:27 ET

Orvana Announces NI 43-101 Resource Estimate at Copperwood

TORONTO, ONTARIO--(Marketwire - March 22, 2010) - Orvana Minerals Corp. (TSX:ORV) announced today a National Instrument ("NI") 43-101-compliant mineral resource estimate from the Copperwood stratiform copper deposit located in the Upper Peninsula, Michigan, USA. Measured and Indicated resources are 19.5 million tonnes of 1.86% copper for 798 million pounds of copper, and Inferred resources are 3.3 million tonnes of 1.49% copper for 107 million pounds copper. The Technical Report will be filed with SEDAR within 45 days.

"The total copper inventory at Copperwood has been increased by 12% from the historic estimates. These data will be used to evaluate the trade-off studies and refine our conceptual mine plan, and will be incorporated into a Preliminary Economic Assessment which will be released before the end of June, 2010." said Bill Williams, Vice President, Corporate Development.


Copperwood is located along the southern flank of the WNW-plunging Western Syncline. The main mineralization occurs as very fine-grained chalcocite in the Domino (dark-gray siltstone and black laminated shale) and Upper Layer (red massive, gray laminated and occasionally red laminated siltstones) Units, respectively, together called the "copper-bearing sequence" ("CBS"), at the base of the Proterozoic Nonesuch Formation, which dips from 7o to 12o north. The CBS lies about 30 metres below an unconsolidated clay in the south and is as deep as 289 metres approximately 1.75 kilometres to the north.

Resource Estimate

The resource estimate is based on 119 drill holes totaling 18,885 metres of which 85 holes totaling 13,425 metres are from Orvana drilling and the balance historical. The mineralized area is truncated to the south by subcrop, to the north and east by a stratigraphic pinch out, and to the west by the lake shore. It is open to the southwest. The mineral resource estimate is summarized in the following table.

Table 1: Copperwood Mineral Resources, Effective Date 11 March 2010 (Dr. Harry Parker, P. Geo.,)

Category Tonnage Thickness Copper Copper
  million tonnes meters (%) (million lbs)
Measured 7.79 1.66 2.56 439
Indicated 2.48 1.22 2.39 131
Measured and Indicated 10.27 1.53 2.52 570
Inferred 1.30 0.95 2.29 65
Upper Layer        
Category Tonnage Thickness Copper Copper
  million tonnes meters (%) (million lbs)
Measured 6.35 1.35 1.15 161
Indicated 2.85 1.39 1.07 67
Measured and Indicated 9.20 1.36 1.13 228
Inferred 1.97 1.43 0.96 42
Combined Domino and Upper        
Category Tonnage Thickness Copper Copper
  million tonnes meters (%) (million lbs)
Measured 14.15 3.01 1.93 600
Indicated 5.33 2.60 1.69 198
Measured and Indicated 19.47 2.89 1.86 798
Inferred 3.27 2.38 1.49 107

Note: Assumptions used in assessing prospects of economic extraction are noted below

In addition to copper, the Copperwood deposit hosts silver values ranging from 5 grams per tonne (gpt) to 7 gpt in both the Domino and Upper Layer. Silver will likely report with chalcocite in a concentrate but additional metallurgical test work is required to support declaration of measured silver mineral resources.

The Company has option agreements on three other mineralized areas located within the Western Syncline. Historical estimates, which are not NI 43-101 compliant, of 45.5 million tonnes at 1.23% copper for about 1.25 billion pounds of copper were delineated in these areas during the 1950s (see July 9, 2009 press release). The historical estimates cited herein were completed by an independent consultant in 1974 and were considered "firm", which has no equivalent category under CIM Definition Standards (2005). These estimates are conceptual in nature and cannot be relied upon.

Preliminary Economic Assessment

The Company has conducted various trade-off studies over the last 12 months. These studies included the evaluation of mine and tailings impoundment designs as well as the assessment of a water source, waste management, and transportation alternatives. Currently, the conceptual plan uses room-and-pillar methods and a variation of a continuous miner; pillars are planned to be removed at an opportune time, which will likely result in a higher recovery than the base case cited below.

KD Engineering, Tucson, Arizona, under the supervision of Joseph Keane, P.E., an independent qualified person for the purposes of National Instrument ("NI") 43-101, has been contracted to complete the Preliminary Economic Assessment.


Security measures were taken to ensure the integrity and validity of the CBS and proximal rocks in the new drill core. The core was sampled based on the lithostratigraphy established by the Copperwood geologic team. Assays were completed by Activation Laboratories Ltd., an ISO/IEC 17025 and CAN-P- 1579 registered laboratory. The QA/QC protocol included internal and laboratory certified reference materials, blanks, duplicates and check assays. Copper and silver were determined using an agua regia extraction with an Optical Emission Spectrometry (OES) finish.

Qualified Persons

The technical information contained in this document was prepared under the supervision of Bill Williams, Ph.D., Vice President, Corporate Development, a qualified person for purposes of NI 43-101. AMEC E & C Services, Inc., Phoenix, Arizona under the supervision of Dr. Harry Parker, a qualified person who is independent of Orvana for the purposes of NI 43-101, prepared the resource estimate and the information related to it.

Assumptions Used in Assessing Prospects of Economic Extraction

In assessing prospects of economic extraction AMEC has made a conceptual economic analysis to determine an economic cut-off grade using the following economic assumptions:

  • Mining Cost $22/t mined
  • Processing Cost $9.00/t milled
  • G&A Cost $4.00/t milled
  • Smelting, Refining, Freight Cost $5.63/t milled
  • Copper Price $2.30/lb
  • Mill Recovery 87%
  • Smelter Payable 95%
  • Mining Dilution 7.5%

In addition AMEC assumed:

  • A production rate of 4,000 to 5000 tonnes per day (tpd)
  • Underground mining using a room and pillar method with no backfill
  • Mining recovery from 65 to 70%
  • Average mining heights of approximately 3 m (9 ft)
  • Minimum mining height of 1.5 m (5 ft)

These assumptions have been used to assess whether there are reasonable prospects for economic extraction using analogies to similar deposits. However economic viability of the Copperwood mineral resource can only be demonstrated by Pre-Feasibility and Feasibility Studies, and there is no assurance that the stated resources can be upgraded in confidence and converted to reserves.

The assumption of 65% to 70% mining recovery is a base case.

About Orvana

Orvana Minerals is a gold producer with a strong balance sheet and is transforming itself into a multi-mine gold and copper producer. Orvana owns and operates the copper-gold Don Mario Mine in Bolivia and is developing the advanced-stage El Valle-Boinas/Carles´gold-copper project in northern Spain and the Copperwood copper project in Michigan, USA. Additional information is available at Orvana's website (www.orvana.com).

Forward Looking Disclaimer

Certain statements in this press release constitute forward-looking statements or forward-looking information within the meaning of applicable securities laws ("forward-looking statements"). Any statements that express or involve discussions with respect to predictions, expectations, beliefs, plans, projections, objectives, assumptions, potentials, future events or performance (often, but not always, using words or phrases such as "believes", "expects" "plans", "estimates" or "intends" or stating that certain actions, events or results "may", "could", "would", "might", "will" or "are projected to" be taken or achieved) are not statements of historical fact, but are forward-looking statements.

Forward-looking statements relate to, among other things, all aspects of the development of the Copperwood project and its potential development, operation and production.

Forward-looking statements are necessarily based upon a number of estimates and assumptions that, while considered reasonable by Orvana as of the date of such statements, are inherently subject to significant business, economic and competitive uncertainties and contingencies. The estimates and assumptions of Orvana on which statements in this news release are based may prove to be incorrect, and they include, but are not limited to, the various assumptions set forth herein and in the Company's most recently filed Annual Information Form as well as permitting and development at the Copperwood project being consistent with the Company's current expectations.

A variety of inherent risks, uncertainties and factors, many of which are beyond the Company's control, affect the operations, performance and results of the Company and its business, and could cause actual results to differ materially from estimated or anticipated events or results expressed or implied by forward looking statements in this press release. Some of these risks, uncertainties and factors include the Company's ability to obtain and maintain all necessary regulatory approvals and licenses; risks generally associated with mineral exploration and development, including the Company's ability to develop the Copperwood project; and the risks identified in Orvana's Annual Information Form.

Forward looking statements are based on management's current plans, estimates, projections, beliefs and opinions, and except as required by law, the Company does not undertake any obligation to update forward looking statements should assumptions related to these plans, estimates, projections, beliefs and opinions change. Readers are cautioned not to put undue reliance on forward-looking statements.

Contact Information

  • Orvana Minerals Corp.
    Jane Watson
    Investor Relations
    (647) 221-9505
    Orvana Minerals Corp.
    Roland Horst
    Chief Executive Officer
    Orvana Minerals Corp.
    Carlos Mirabal
    President and Chief Operating Officer
    Orvana Minerals Corp.
    Bill Williams
    Vice-President, Corporate Development
    Orvana Minerals Corp.
    Don Gray
    Vice-President, Mining