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Dia Bras Drifts into New Bornite Zone at its Bolivar Mine, Chihuahua, Mexico
Montréal, Québec, - May 28, 2008 -
Dia Bras Exploration Inc. is pleased to report that during the course of its pilot-mining activities at its Bolivar Mine (Alta Ley) property, a new wide zone of copper-zinc mineralization has been exposed below the San Angel zone on Level 2 of the mine. A highly altered granodiorite dyke, of variable width (5-20 metres), carrying bornite mineralization and producing a halo of alteration and copper-zinc mineralization on its margins, has been exposed in the workings.
“The discovery of this new zone is very exciting” says François Auclair, Vice-President, Exploration. “The presence of abundant bornite indicates that the zone is a higher-temperature portion of the mineralizing system that generated the Bolivar mineralization. This is the second important bornite zone that we have encountered, the first being at El Gallo several hundred metres south of this one (see press release April 8, 2008). The granodiorite dyke displays strong alteration and mineralization, and could be one of the feeder systems of the Upper Skarn horizon of the Bolivar mine. Furthermore, the fact that we have intersected the dyke in drill holes more than 125 metres ESE of the Selena workings indicates potential for a large volume of Cu-Zn rich mineralized rock in this area, thereby adding more value to our Bolivar mine.”
Click here t view the San Angel mineralization pictures.
The dyke can be traced from Level 2 to Level 8 of the mine, a vertical extent of at least 100 metres, and over a lateral distance of approximately 125 metres in an ENE direction, in the Breccia Linda trend, about 25 metres below the mined out Breccia Linda zone. Mineralisation associated with the dyke had been intersected by drilling in 2004, but at the time its importance was not properly recognised (DB04B098: 215m to 218m core length: 2.28% Cu, 15.62% Zn, 21.6 g/t Ag and 0.05 g/t Au). The dyke is inferred to be the feeder for the manto-type mineralization of the Breccia Linda.
The Breccia Linda was the largest and richest zone of mineralization discovered, developed and mined by Dia Bras.
Click here to view the surface plan of the Bolivar underground workings and mineralized trends.
Additional detailed drilling and drifting will be required to determine the dyke’s overall size and continuity. A 10,000 metres definition drill program underway is expected to result in an increase of the measured and indicated resources at the Bolivar Atla Ley sector, especially within the known Titanic and Selena massive sulphide lenses (along the Fernandez trend) and also along this newly discovered zone.
The granodiorite dyke strikes ENE, but appears to be truncated or dismantled along its trend. In the San Angel zone, it displays a stock-like appearance – wider and thicker – and appears to be underneath the usual mineralisation of the Upper Skarn. At the moment, it can be traced for at least 125 metres along strike, with variable widths ranging from 5 to 20 metres. At its contact with the surrounding skarn, it displays strong metasomatic and metamorphic aureole interaction with the surrounding host skarn or andesitic dyke, where hornfels and skarn were generated within marble layers. These contacts are themselves mineralised with sphalerite, chalcopyrite, bornite, magnetite, and silver sulphides. It is possible that this mineralization could connect with the Selena Inferior zone, observed on level 8-990 and in holes 200 and 213.
Mineralisation of sphalerite, chalcopyrite, bornite and magnetite is found encapsulated in the andradite-grossularite skarns as well as in the wollastonite marble. The mineralization is present in many different forms: massive bodies, in fracture-filling of the wallrocks, and disseminated.
In the San Angel zone, the highest assays were found in sample 23-100505 with 21.89% Zn and in sample 7-121214 with 15.70% Cu. The table below shows selected samples from this zone. From all the samples collected, average grades of 1.5% - 2.0% Cu, 5% - 7% Zn and 50 – 80 g/t Ag were found. However, some are still pending, and the table of all the samples collected can be viewed at the following link http://www.diabras.com/en/newscenter/2008/Pr12CompleteSampleAssaysSanAngel.pdf
Selected samples of the San Angel Zone
San Angel Zone
Variable |
||||
Sample |
Cu |
Zn |
Ag g/t |
|
100505 |
1.83 |
21.89 |
60 |
|
121198 |
1.70 |
11.07 |
50 |
|
121199 |
0.19 |
3.28 |
20 |
|
Sub Level 840 SAN ANGEL |
||||
Sample |
Cu |
Zn |
Ag g/t |
|
121209 |
3.03 |
20.7 |
40 |
|
121214 |
15.70 |
19.43 |
190 |
|
121215 |
1.83 |
8.74 |
30 |
|
Sub Level 850 SAN ANGEL |
||||
Sample |
Cu |
Zn |
Ag g/t |
|
121236 |
3.22 |
2.69 |
240 |
|
121270 |
3.89 |
1.16 |
210 |
|
121271 |
2.87 |
0.22 |
290 |
|
121272 |
3.07 |
3.29 |
280 |
|
121276 |
3.11 |
0.48 |
300 |
|
121277 |
7.10 |
1.61 |
610 |
|
121278 |
1.05 |
16.07 |
70 |
|
121202 |
3.75 |
21.51 |
50 |
|
121252 |
2.23 |
12.16 |
150 |
|
121299 |
1.00 |
12.81 |
10 |
|
Click here to view the San Angel Section A060S09825.
Click here to view the Excavation Sampling - San Angel Level 2 and table of assays.
Method of analysis
Samples from underground working at Bolivar have been analysed at the Nichromex lab facilities in Malpaso, Chihuahua state, Chihuahua. Samples are analysed for Cu, Zn, Pb and Ag by AA.
Core drill holes samples were prepared at the Chemex lab facility in Chihuahua, Mexico, and analyzed by ICP and AA methods at their facilities in Vancouver, Canada. Diamond drill samples sent for analysis consisted of half NQ-size diamond core split on-site, prepared by the ALS Chemex sample preparation laboratory in Chihuahua, Mexico, 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 done by Induction Coupled Plasma (ICP) at Chemex.
Quality control
The quality assurance-quality control (QA-QC) of Dia Bras has been described in detail in both Roscoe Postle and Associate’s NI43-101 reports of December 2006 at Cusi and October 2005 for Bolivar.
The technical content of this news release has been approved by François Auclair. P. Geo. and Vice-President, Exploration of Dia Bras, a Qualified Person as defined in NI43-101.
About Dia Bras
Dia Bras is a Canadian mining and exploration company focused on precious and base metals in Mexico. The Company is committed to developing and adding value to its assets – the Bolivar copper-zinc project, the Cusi silver mining camp in the renowned Sierra Madre mining district of northern Mexico, and La Engañosa copper-silver property in the State of Jalisco. The Company trades on the TSX Venture Exchange under the symbol “DIB”.
For further information on Dia Bras, visit www.diabras.com or contact:
Daniel Tellechea |
|
François Auclair |
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