Minefinders Corporation Ltd.
TSX : MFL
AMEX : MFN

Minefinders Corporation Ltd.

June 12, 2007 08:00 ET

Minefinders Receives New Audit of Dolores Project Resources-Measured and Indicated Gold and Silver Grow by More Than 20%

VANCOUVER, BRITISH COLUMBIA--(Marketwire - June 12, 2007) - Minefinders Corporation Ltd. (the "Company" or "Minefinders") (TSX:MFL)(AMEX:MFN) is pleased to report the results from an updated audited resources estimation for its Dolores gold and silver project in Chihuahua, Mexico.

The new resources estimation was prepared by the Company and audited by Chlumsky, Armbrust, and Meyer ("CAM") of Denver, Colorado. It is the first audited estimation of resources at Dolores since a November 2004 report, upon which the current Dolores Feasibility Study (announced February 27, 2006) and mine economics were based.

The new report shows an increase of 23.1% in contained gold and 21.3% in contained silver at a 0.4 grams per tonne ("gpt") gold equivalent ("Aueq")(i) cutoff in the "measured and indicated" category, when compared to the previous audited resources (as reported by the Company on December 6, 2004). An additional "inferred" resource of 30.35 million tonnes, containing 661,000 ounces of gold and 27.5 million ounces of silver, is delineated in the new model.



Table 1: Dolores Project - Audited Measured and Indicated Resources
Estimates - April 2007
--------------------------------------------------------------------------
Cutoff Aueq
Grade Gold Silver Grade Aueq
(i) Grade Gold Grade Silver (ii) (ii)
(gpt) Tonnes (gpt) (ounces) (gpt) (ounces) (gpt) (ounces)
--------------------------------------------------------------------------
3.0 10,571,000 3.844 1,306,000 155.3 52,769,000 6.432 2,186,000
2.0 20,225,000 2.721 1,769,000 114.6 74,539,000 4.632 3,012,000
1.0 45,077,000 1.680 2,435,000 76.1 110,305,000 2.949 4,273,000
0.6 73,436,000 1.202 2,838,000 56.0 132,095,000 2.135 5,039,000
0.5 88,295,000 1.052 2,987,000 49.5 140,531,000 1.877 5,329,000
0.4 106,292,000 0.918 3,137,000 43.5 148,743,000 1.643 5,616,000
0.3 123,382,000 0.819 3,249,000 39.0 154,826,000 1.470 5,829,000
--------------------------------------------------------------------------
(i) cutoff based on gpt Aueq at a 75:1 silver to gold ratio, having
regard to metallurgical recoveries
(ii) based on updated 60:1 silver to gold ratio, without regard to
metallurgical recoveries


Minefinders President, Mark Bailey, stated: "We have consistently increased the size and quality of the gold and silver resources at our Dolores project - and continue to do so, with two rigs now drilling on site. The CAM audit again confirms the quality and integrity of the hard work of our employees and consultants.

"The updated resources model will be incorporated into the Dolores open-pit mine plan. The substantial increase in measured and indicated resources, and in metal prices, since our bankable feasibility study, implies a significant improvement in project economics, which we will quantify with new mine planning and reserves definition.

"The new model also supports a decision to move forward aggressively with pre-feasibility studies toward an underground mine plan and the addition of a mill process facility that will significantly increase recoveries from high-grade zones within the open pit and future underground mining operations."

The new report shows increases in estimated measured and indicated resources of 589,000 ounces of gold and 26,131,000 ounces of silver, at the 0.4 gpt Aueq cutoff, compared with the audited resource used in the Feasibility Study, as set out below:



Table 2: Dolores Project - Audited Resources Estimates and % Increases at
0.4 gpt Aueq(i) cutoff - April 2007
--------------------------------------------------------------------------
Resource 2007 Audited Resource 2004 Audited Resource
--------------------------------------------------------------------------
At cutoff
grade
0.4 gpt Gold Silver Gold Silver
Aueq(i) Tonnes (ounces) (ounces) Tonnes (ounces) (ounces)
--------------------------------------------------------------------------
Measured &
Indi-
cated 106,292,000 3,137,000 148,743,000 85,272,000 2,548,000 122,612,000
(%
Increase) (+24.7%) (+23.1%) (21.3%)
--------------------------------------------------------------------------
Inferred 30,350,000 661,000 27,517,000 22,223,000 631,000 22,533,000
(%
Increase) (+36.6%) (+4.8%) (+22.1%)
--------------------------------------------------------------------------
(i) cutoff based on gpt Aueq at a 75:1 silver to gold ratio, having regard
to metallurgical recoveries


Complete tables of all resource categories and cutoff grades are attached to this news release.

The new NI 43-101 compliant resource estimation model includes results from drilling through to the end of 2006 and incorporates updated geologically constrained grade envelopes. It will be the basis for updated reserve definition and open-pit mine planning and for the development of an underground mine plan and reserves. The report will shortly be filed on SEDAR and made available on the Company's website.

Impact of Updated Resource Estimation

The updated block model expands resources in two critical areas that are likely to have an impact on the final open pit mine design:

- Additional high-grade resources were intersected to the north of the lower breccia pipe area (a zone of persistent high-grade mineralization that hosts a substantial portion of the deposit's high-grade reserves). This is expected to drive the extension of the open pit design in this area, with an attendant increase in overall reserves; and

- Resources at the southern boundary of the open pit mine plan have been converted from the "inferred" into the "measured and indicated" categories. Previous work had concluded that this reclassification should allow for expansion of the open pit plan to the south to incorporate this mineralization, thereby increasing the total amount of metal mined, improving access to the southern portion of the pit, and improving haul road efficiency.

Reserves Update

The updated resource model will be incorporated into the open-pit mine plan so as to permit the definition of new mine reserves. The substantial increase in measured and indicated resources and current metal prices imply a significant improvement in project economics since the previous economic analysis in the Feasibility Study, based on the 2004 resource model. The previous analysis was based on metal prices of $475/oz gold and $7.50/oz silver.

Underground Resource Definition

The additional drilling reflected in the new resources model has increased our understanding of the geometry, grade, and tenor of mineralization below the planned open pit mine. The drilling has confirmed sufficient underground high-grade resource to support a pre-feasibility study to develop the underground portion of the Dolores deposit. Based on a positive pre-feasibility study, an exploration/production decline will be constructed to provide access to further define and develop reserves in conjunction with initiating underground mining operations. With an aggressive budget, it is anticipated that these resources could be brought into production within a three to four year period.

Methodology - Resources Estimation

Resources estimates were based upon interpolated block grades, constrained by 3D wireframe models constructed with Gemcom software. Block grade estimation was performed using inverse distance to the fifth power weighting ("ID5"). CAM re-estimated the block grades as a check of the resource estimation methods used. In CAM's opinion: "The Dolores block model provides a reasonable estimate of mineral resources at Dolores."

Resource blocks are classed as "measured", "indicated", or "inferred", in accordance with the confidence level of the estimate. Resource classification was determined using the anisotropic distance to the nearest composite. Blocks within approximately 17.5 meters of the nearest composite were assigned to the "measured" category. "Indicated" blocks are between 17.5 meters and 35 meters from a composite; while "inferred" blocks are between 35 meters and 90 meters from the nearest composite. Composites were capped to 30 g/t gold and 1,000 g/t silver, prior to grade estimation. For additional reference, please see the Company's December 6, 2004 news release.

For the purpose of geological modeling and the application of a cut-off grade, gold and silver grades were rendered into a gold equivalent grade calculated at a silver to gold ratio of 75:1, based on prices of US$5.00 per ounce of silver and US$300 per ounce of gold and metallurgical recoveries.

Methodology - Fieldwork

The resource estimation is based on 412 diamond drill core holes (124,921 meters) and 226 reverse circulation holes ("RC") (43,067 meters) for a total of 167,998 meters. Drilling was completed between October 1996 and December 2006. RC drill samples were taken every 1.52 meters (5 feet). Diamond drill core sample length was variable, based on lithology and mineralization, but was typically 2 meters in length. The core was split with one-half retained for reference.

Quality Control and Assurance

All analyses are fire assay analyses for gold and multi-acid digestion with AA analyses or fire assay analyses for silver, and completed by either Chemex Labs of Vancouver, Canada, or Inspectorate Labs of Sparks, Nevada. Robert Sandefur P.E., of Chlumsky, Armbrust, and Meyer, is the "qualified person" responsible for the contents of the CAM NI 43-101 report to be filed on SEDAR.

Mark Bailey MSc., P.Geo., is the "qualified person" with overall responsibility for the Dolores Project and is responsible for the contents of this news release.

About Minefinders

Minefinders is a successful precious metals exploration company. It is currently constructing the 18,000 tonnes per day Dolores open pit gold and silver mine in Chihuahua, Mexico.

The Company continues exploration to expand the gold and silver resources on the Dolores property for future development. In addition, it has commenced follow-up programs of exploration drilling on its Planchas de Plata and Real Viejo projects in Sonora, Mexico and initial drilling on its Gutsy gold prospect in the Carlin Trend of Nevada.

The Company continues to evaluate other opportunities in the Americas and has recently added to its already significant holdings of mineral concessions in Mexico.

MINEFINDERS CORPORATION LTD.

Mark H. Bailey, President and Chief Executive Officer

Safe Harbor Statement under the United States Private Securities Litigation Act of 1995: Statements in this release that are forward-looking, including statements relating to the size, and potential growth in size, of the Company's mineral reserves and resources, the economic feasibility of, and the nature and timing of mine construction and mining operations at, the Company's Dolores Project and the further exploration and development of the Company's mineral projects, are subject to various risks and uncertainties concerning the specific factors identified above and in the Company's periodic filings with the Ontario Securities Commission and the U.S. Securities Exchange Commission ("SEC"). Such information contained herein represents management's best judgment as of the date hereof based on information currently available. The Company does not intend to update this information and disclaims any legal liability to the contrary.

National Instrument 43-101 and the Canadian Institute of Mining and Metallurgy Classification system. These standards differ significantly from the requirements of the United States Securities and Exchange Commission, and resource information reported in this disclosure may not be comparable to similar information reported by United States Companies. The terms "resource(s)" does not equate to "reserves" and normally may not be included in documents filed with the Securities and Exchange Commission.

Cautionary Note to U.S. Investors: The SEC permits mining companies to disclose only those mineral deposits that can be extracted or produced economically in their filings with the SEC. This news release uses the term "inferred resource" that the SEC guidelines prohibit from inclusion in filings with the SEC.



Table 3: Dolores Project - Audited Resources Estimates - April 2007

Measured Resources
--------------------------------------------------------------------------
Cutoff Aueq
Grade Gold Silver Grade Aueq
(i) Tonnes Grade Gold Grade Silver (ii) (ii)
(gpt) (000s) (gpt) (ounces) (gpt) (ounces) (gpt) (ounces)
--------------------------------------------------------------------------
3.0 5,899 3.978 754,000 162.7 30,849,000 6.689 1,269,000
2.0 11,034 2.820 1,000,000 119.7 42,460,000 4.815 1,708,000
1.0 24,686 1.723 1,367,000 77.9 61,862,000 3.022 2,398,000
0.6 38,786 1.257 1,568,000 58.5 72,904,000 2.231 2,783,000
0.5 45,568 1.116 1,635,000 52.4 76,814,000 1.990 2,915,000
0.4 54,092 0.980 1,705,000 46.5 80,788,000 1.754 3,051,000
0.3 62,435 0.876 1,758,000 41.8 83,832,000 1.572 3,155,000
--------------------------------------------------------------------------

Indicated Resources
--------------------------------------------------------------------------
Cutoff Aueq
Grade Gold Silver Grade Aueq
(i) Tonnes Grade Gold Grade Silver (ii) (ii)
(gpt) (000s) (gpt) (ounces) (gpt) (ounces) (gpt) (ounces)
--------------------------------------------------------------------------
3.0 4,672 3.674 552,000 145.9 21,921,000 6.106 917,000
2.0 9,191 2.602 769,000 108.6 32,079,000 4.411 1,304,000
1.0 20,392 1.629 1,068,000 73.9 48,443,000 2.860 1,875,000
0.6 34,650 1.140 1,270,000 53.1 59,191,000 2.025 2,256,000
0.5 42,727 0.984 1,352,000 46.4 63,717,000 1.757 2,414,000
0.4 52,200 0.853 1,432,000 40.5 67,954,000 1.528 2,565,000
0.3 60,947 0.761 1,491,000 36.2 70,994,000 1.365 2,674,000
--------------------------------------------------------------------------

Measured Plus Indicated Resources
--------------------------------------------------------------------------
Cutoff Aueq
Grade Gold Silver Grade Aueq
(i) Tonnes Grade Gold Grade Silver (ii) (ii)
(gpt) (000s) (gpt) (ounces) (gpt) (ounces) (gpt) (ounces)
--------------------------------------------------------------------------
3.0 10,571 3.844 1,306,000 155.3 52,769,000 6.432 2,186,000
2.0 20,225 2.721 1,769,000 114.6 74,539,000 4.632 3,012,000
1.0 45,077 1.680 2,435,000 76.1 110,305,000 2.949 4,273,000
0.6 73,436 1.202 2,838,000 56.0 132,095,000 2.135 5,039,000
0.5 88,295 1.052 2,987,000 49.5 140,531,000 1.877 5,329,000
0.4 106,292 0.918 3,137,000 43.5 148,743,000 1.643 5,616,000
0.3 123,382 0.819 3,249,000 39.0 154,826,000 1.470 5,829,000
--------------------------------------------------------------------------

Inferred Resources
--------------------------------------------------------------------------
Cutoff Aueq
Grade Gold Silver Grade Aueq
(i) Tonnes Grade Gold Grade Silver (ii) (ii)
(gpt) (000s) (gpt) (ounces) (gpt) (ounces) (gpt) (ounces)
--------------------------------------------------------------------------
3.0 1,429 3.668 169,000 110.8 5,093,000 5.515 253,000
2.0 2,961 2.597 247,000 85.4 8,130,000 4.020 383,000
1.0 8,327 1.448 388,000 55.6 14,882,000 2.374 636,000
0.6 19,050 0.895 548,000 36.7 22,509,000 1.507 923,000
0.5 24,227 0.776 605,000 32.2 25,108,000 1.314 1,023,000
0.4 30,350 0.677 661,000 28.2 27,517,000 1.147 1,120,000
0.3 36,296 0.603 704,000 25.2 29,380,000 1.022 1,193,000
--------------------------------------------------------------------------
(i) cutoff based on gpt Aueq at a 75:1 silver to gold ratio, having
regard to metallurgical recoveries
(ii) based on updated 60:1 silver to gold ratio, without regard to
metallurgical recoveries


Contact Information

  • Minefinders Corporation Ltd.
    Mark H. Bailey
    President and Chief Executive Officer
    1-866-687-6263
    (604) 687-6267 (FAX)
    Website: www.minefinders.com