Dia Bras Provides Resource Information on its New Promontorio Silver Disseminated Deposit at Cusi and Updates Resources at the Bolivar Property
TORONTO, ONTARIO -- (Marketwire) -- 11/23/11 -- Dia Bras Exploration Inc. (TSX VENTURE: DIB) ('Dia Bras' or the 'Company') is pleased to report that its own geological and mining staff has calculated a Resource Evaluation for a portion of its Cusi property, which is along Section A of the disseminated silver zone at the Promontorio mine. The Company has also completed an updated Resource Evaluation for the Bolivar copper-zinc-silver project after the start-up of its new Piedras Verde mill.
'These results illustrate the importance of our recent silver discovery at our Cusi property' stated Daniel Tellechea, President and CEO of Dia Bras Exploration. 'Our recent work at the Cusi property has shown exciting results that have increased markedly the tonnage potential of the property due to our discovery at the Promontorio mine of wide mineralized zones with high silver grades for a disseminated-type mineralization. We are pleased to show this potential by the results of our resource calculation of only a small fraction of this zone. I also highlight, for instance, Block 1 of Section A zone that contains an estimated 50,000 tonnes with an estimated silver grade of 759 grams per tonne, reflecting the remarkable high quality and volume in this zone.'
Mr. Tellechea continued, 'With respect to our Bolivar copper-zinc-silver property, the company has six years of pilot mining data that provide factual information on the metallurgy of the copper and zinc mineralization, recovery rates, per tonne revenues at various commodity prices, mining costs and other factors. With the commissioning in September of the 1,000 tonnes-per-day Piedras Verde mill on site, we have significantly lowered our direct operating costs and expanded our production. We are very excited about the future of the Bolivar property as we plan to double milling capacity over the next year to 2,000 tonnes per day.'
These mineral resources estimates for both projects have not resulted in a material change in resources on either property as presented in 43-101 reports prepared in the past despite several years of production from pilot-mining. However, it represents an important quality upgrade for Cusi because these ounces are in wide mineralized zones up to 25 meters thick versus the prior resources that were defined on vein structures approximately one meter in width.
Promontorio Section A Resources, Cusi Property:
The Company has identified 2.7 million ounces of silver resources on Section A of the Promontorio silver disseminated zone (Figure 1: http://diabras.com/files/media/7f690_figure1.pdf), which remains open in at least two directions and more importantly to depth. Indicated Resources are shown in Table 1 and Inferred Resources in Table 2.
---------------------------------------------------------------------------
Table 1: Indicated Resources on Section A
---------------------------------------------------------------------------
Block (Figure 1) Tonnage Ag g/t Pb %
---------------------------------------------------------------------------
1 50,000 759 0.36
---------------------------------------------------------------------------
2 40,000 141 0.32
---------------------------------------------------------------------------
3 10,000 79 0.16
---------------------------------------------------------------------------
4 50,000 254 0.13
---------------------------------------------------------------------------
5 50,000 287 0.17
---------------------------------------------------------------------------
6 70,000 152 0.11
---------------------------------------------------------------------------
7 15,000 189 0.09
---------------------------------------------------------------------------
15% dilution 42,750 -
---------------------------------------------------------------------------
Total 327,750 261 0.17
---------------------------------------------------------------------------
Estimated Total Contained Silver: 2,750,570 ounces
---------------------------------------------------------------------------
---------------------------------------------------------------------------
Table 2: Inferred Resources on Section A
---------------------------------------------------------------------------
Block Tonnage Ag g/t Pb %
---------------------------------------------------------------------------
A 6,250 343 1.04
---------------------------------------------------------------------------
B 37,500 138 0.55
---------------------------------------------------------------------------
15% dilution 6,562 - -
---------------------------------------------------------------------------
Total 50,312 147 0.54
---------------------------------------------------------------------------
Estimated Total Contained Silver: 237,809 ounces
---------------------------------------------------------------------------
The Company has estimated the Mineral Resources of Section A of the Promontorio disseminated silver deposit using the database as of 20th of October 2011, which includes 111 diamond surface and underground drill holes, 73 of which were drilled during 2006-2007 and 38 recently, for a total of 21,706.8 metres of drilling (12,252.9 during 2006-2007 and 9,453.9 after). A total of some 285.9 metres of assayed core was used (247 samples) for the resources calculation corresponding to 6 surface drill holes (3 during 2007 and 3 after) for a total of 1,130.5 metres.
The estimate used a dilution factor of 15%, a specific gravity of 2.5 g/cc, and a cut-off grade of 126 g/t Ag and 0.17% Pb based on average prices for silver as well production costs and expected recovery in the resource model. The cutoff grade is based on metal price assumption of US$31.93/oz Ag and 0.8999 $/lb Pb. The concentrations of Zn and Au are too low to affect the resource calculation and are not shown in the tables. Production costs are as determined by Dia Bras for underground mining at Cusi and operation of the Malpaso mill.
The Resources of Section A of the disseminated zone were calculated by a combination of the three following methods:
-- Equal end areas considering that the mineralization varies linearly
between sections.
-- Distance of influence of a section equal to the sum of the half-distance
on each side and area average.
-- Influence distance equal to the sum of half-distances and total length
of tranche.
Bolivar Resource Evaluation:
Effective October 1st, 2011, resources from the Bolivar project (Figure 2: http://diabras.com/files/media/7177b_figure2.pdf) total 3,134,535 tonnes at 1.07% Cu, 0.78% Zn, 0.219 g/t Au and 26 g/t Ag in the Indicated Resource category and 2,953,028 tonnes at 1.25% Cu, 0.40% Zn, 0.274 g/t Au and 26g/t Ag in the Inferred Resources category (see tables 3 & 4). These estimates include a 10% mine dilution factor.
---------------------------------------------------------------------------
Table 3: Indicated Resources, Bolivar Cu-Zn-Ag Deposit
Dilution 10%
---------------------------------------------------------------------------
Body (Figure 2) Tonnage Cu Zn Au Ag
% % g/t g/t
---------------------------------------------------------------------------
La Narizona 37,184 0.50 8.77 0.020 30
---------------------------------------------------------------------------
Gallo Superior Cu-Zn 501,859 1.86 1.74 0.330 50
---------------------------------------------------------------------------
Gallo Superior Cu-mt 187,767 1.98 0.14 0.200 33
---------------------------------------------------------------------------
Gallo Inferior Cu-Au-
mt 827,243 1.57 0.15 0.440 31
---------------------------------------------------------------------------
Rosario Cu-Zn-mt 64,154 0.45 3.47 0.030 11
---------------------------------------------------------------------------
La Increible 791,699 0.63 0.46 0.020 18
---------------------------------------------------------------------------
Bolivar NW 385,599 0.34 0.85 0.190 13
---------------------------------------------------------------------------
San Francisco 54,071 1.15 3.49 0.501 37
---------------------------------------------------------------------------
Dilution (10%) 284,958 - - - -
---------------------------------------------------------------------------
Sum & Average 3,134,535 1.07 0.78 0.219 26
---------------------------------------------------------------------------
---------------------------------------------------------------------------
Table 4: Inferred Resources, Bolivar Cu-Zn-Ag Deposit
Dilution 10%
---------------------------------------------------------------------------
Body Tonnage Cu Zn Au Ag
% % g/t g/t
---------------------------------------------------------------------------
Gallo Superior Cu-Zn 383,100 2.16 0.99 0.260 45
---------------------------------------------------------------------------
Gallo Superior Cu-mt 134,750 2.16 0.10 0.230 34
---------------------------------------------------------------------------
Gallo Inferior Cu-Au-mt 1,512,963 1.50 0.22 0.420 30
---------------------------------------------------------------------------
Rosario Cu-Zn-mt 50,000 0.51 2.71 0.030 14
---------------------------------------------------------------------------
La Increible 431,348 0.49 0.37 0.020 15
---------------------------------------------------------------------------
Bolivar NW 172,410 0.34 0.85 0.190 13
---------------------------------------------------------------------------
Dilution (10%) 268,457 - - - -
---------------------------------------------------------------------------
Sum & Average 2,953,028 1.25 0.40 0.274 26
---------------------------------------------------------------------------
The Mineral Resources estimate for the Bolivar deposit used a cut-off grade based on average prices for copper, zinc, silver and gold, as well as production costs and expected recovery in the resource model. The specific gravity (sg) varies by block, between 3.0 and 3.5 g/cc, depending on the content of sulfide minerals and magnetite. The average sg for the Indicated Resources is 3.23 g/cc and for the Inferred Resources it is 3.32 g/cc. The cutoff grades used are: Cu 0.65%, Zn 2.5% and Ag 24 g/t. Production costs are as determined by Dia Bras for underground mining at Bolivar and operation of the Piedras Verdes mill. The cutoff grades are based on metal price assumptions of US$3.2967/lb copper, US$0.8468/lb zinc, US$31.93/oz silver and US$1,650/oz gold.
The Company will continue to move toward increasing Bolivar's Measured and Indicated Resources by conducting additional infill drilling and moving towards a 25 x 25 m hole spacing, as well as step-out drilling to expand the known mineralized zones.
The Company has estimated the Mineral Resources of the Bolivar deposit using the database up to 29th of May 2011, which includes 90 diamond surface and underground drill holes for a total of 17,266.07 metres of drilling. A total of some 1,936.02 metres of assayed core was used (1,876 samples) for the resources calculation.
The resources of the Bolivar mine were calculated by cross sectional method.
During the period 2005-2011, the Company mined 699,224 tonnes of rock averaging 1.65% Cu and 8.34% Zn that were shipped to the Malpaso mill and processed. Malpaso is approximately 300 kilometers from the Bolivar mine, which increased the production costs of the pilot mining but also allowed the Company to explore, test and develop the current operations. Pilot mining also provided important information on metallurgy, recovery rates, mining and milling costs, etc., that are essential in determining the economic viability of a project.
Exploration Potential, Cusi:
As of November 1st, the Company has drilled 36 diamond holes totaling about 9,100 m on the disseminated zone; assays have been returned for 11 holes. The Company continues to drill the Promontorio disseminated zone as well as conducting development drifting on the Promontorio and Santa Eduwiges mines of the Cusi district (see press release of November 15, 2011).
Surface drilling continues at the San Juan and La India deposits, while underground exploration is being conducted at San Juan mine.
Dia Bras' geologists believe that significant potential occurs in the Promontorio disseminated zone as well as below Level 8 of the Santa Eduwiges mine where the San Bartolo vein is being developed. The Santa Eduwiges and Promontorio mines continue to be dewatered in order to enable the Company to access un-mined veins and disseminated zones in both of these areas.
Exploration Potential, Bolivar:
On-going exploration by Dia Bras continues to extend known zones of copper, zinc, silver and gold mineralization at El Gallo mine, La Narizona mine, Alta Ley mine, Increible mine and Bolivar NW deposit of the property, which encompasses some 67 km2. Additional potential has been identified in areas near the Piedras Verde mill. The Los Americanos zone, for example, is only 3 km from the Piedras Verde mill and will be drilled in early 2012.
Method of Analysis
Samples were prepared at the Company's lab facility at its Malpaso lab and analyzed by atomic absorption for Cu, Zn, Pb, Bi, Co, Mn, Sb, Cd and Fe. Gold and silver are analyzed by fire assay method. Diamond drill samples sent for analysis consisted of half NQ-size and BQ-size diamond core split on site. Duplicate samples are sent to the ALS Chemex lab facility in Chihuahua, Mexico, where they are prepped and analyzed by ICP and AA methods at their facilities in Vancouver, Canada, and assayed for Au by 50 g fire assay with AA finish, and for Ag by AA on 50 g split sample at the ALS Chemex North Vancouver Laboratory. Assays for Pb, Zn and Cu are analyzed by Induction Coupled Plasma (ICP) at ALS Chemex.
The Malpaso laboratory follows the quality control methodology recommended by CANMET of Canada, such as assaying of blanks, duplicate samples, and check assays by commercial laboratories such as Chemex.
Quality Control
The quality assurance-quality control (QA-QC) of Dia Bras has been described in detail in both RPA's NI 43-101 reports of December 2006 at Cusi and October 2005 for Bolivar.
The resource calculations reported in this news release were done by Ing. Hector Salas, Exploration Manager Mexico, a licensed engineering geologist (Member, AIMMGEM; Asociacion de Ingenieros de Minas, Metalurgistas y Geologos de Mexico) with 28 years industry experience and a 1984 Bachelor's graduate of Instituto Politecnico Nacional, under the supervision of Thomas L. Robyn, Ph.D., CPG, RPG, a Qualified Person as defined in NI 43-101.
About Dia Bras
Dia Bras Exploration Inc. is a Canadian listed mining company focused on precious and base metals in Peru and Mexico. The Company owns and operates the Yauricocha Mine (Ag-Cu-Zn-Pb) in central Peru and the Bolivar Mine (Cu-Zn-Ag) in Chihuahua State, Mexico. Dia Bras is also pursuing the development and exploration of the Cusi Property (Ag) and exploring several base and precious metals targets In Peru and Mexico.
The Company's shares trade on the TSX Venture Exchange under the symbol 'DIB'.
For further information on Dia Bras Exploration Inc. visit www.diabras.com
Forward-looking Statements
Except for statements of historical fact, all statements in this news release without limitation regarding new projects, acquisitions, future plans and objectives are forward-looking statements which involve risks and uncertainties. There can be no assurance that such statements will prove to be accurate; actual results and future events could differ materially from those anticipated in such statements.
Neither the 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 news release.
Contacts:
Daniel Tellechea
President & CEO
Dia Bras Exploration Inc.
1 (866) 493-9646