VANCOUVER, BRITISH COLUMBIA -- (Marketwire) -- 03/14/13 -- Silver Bull Resources, Inc. (TSX: SVB)(NYSE MKT: SVBL) ("Silver Bull") is pleased to announce that the underground drill program conducted between July 2012 and December 2012 which twinned a series of historical "long hole" drill holes at the eastern end of the "Shallow Silver Zone" and "Zinc Zone" has successfully shown the historical long hole data set is a fair representation of the grade and width of the silver and zinc mineralization in this area. The high correlation between the historical long hole data set and Silver Bull's recently completed core twinning holes means that over 39,000 meters of historical drilling focused in mainly high grade silver and zinc mineralization will now have a more significant influence in any resource calculation at Sierra Mojada.
Discovery of long hole vs surface hole bias in Silver Bull's July 2012 NI43-101 Resource Report: In Silver Bull's most recent NI43-101 resource report on the Sierra Mojada project completed in July 2012 by SRK Consulting (Canada) Inc. ("SRK"), SRK noted that there appeared to be a large apparent bias between surface drill holes and the long hole dataset. As a result, SRK severely restricted the influence of over 2,700 long holes totaling approximately 39,000 meters of drilling in the resource estimation.
In its recommendations in the July 2012 NI43-101 report, SRK recommended that Silver Bull initiate an underground diamond drill program in areas that had been sampled exclusively by long holes and channel samples in order to validate the higher grade portions of the ore body with drill core.
Results for the long hole twinning program: Between July and December 2012, Silver Bull completed over 6,500 meters of underground diamond core drilling, twinning a number of long holes over a 1.5 kilometer east-west strike at the eastern end of the Shallow Silver and Zinc Zones. At the completion of the twinning drill program, Silver Bull engaged SRK to re-evaluate the data to confirm the validity of the historical long hole data set. To do this, SRK ran a series of tests employing various metrics to compare the twin holes with the long holes and surface holes, using 5m by 5m by 5m blocks which represent the block size used in the last resource estimate.
SRK concluded that the grades and widths seen in the historical long hole data set were confirmed by the diamond drilling, and that the twinning program validated this data set. As a result of the twinning program Silver Bull is now able to confidently use the long hole data set with a less restrictive range of influence than has previously been used in any resource estimate for the project.
In its analysis of the data, SRK went on to explain that in comparing the surface drill holes to the long holes in the previous report, the large bias was created due to the fact that these two data sets represented two very different grade domains within the deposit. The long holes are situated in a very high grade domain, while the surface drill holes lie in a lower grade domain. The twinning program demonstrates that there is a marginal bias in the long holes at very high grades ranges but that they agreed well with all core drilling for grades below 125 g/t silver.
Updated NI43-101 Resource Report and JDS Engineering: Silver Bull is now focused on issuing a new NI43-101 resource update and expects this will be out before the end of March 2013. This new report will include over 10,000 meters of additional surface drilling, 6,500 meters of underground drilling, and the increased influence for over 39,000 meters from the long hole data set. For the report, Silver Bull has also updated the geological model for the Sierra Mojada project, continued bulk density data sampling on the various ore types, and collected an additional 400 channel samples for metallurgical test work.
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