Oct 24 2011
Sierra Madre Developments Inc. and Riverside Resources Ltd. have announced results of the recently completed drill program at the El Capitan Target, Penoles Project, Durango State, Mexico. A total of 2,220 meters of HQ core drilling was completed in 18 drill holes.
The El Capitan Target is considered an advanced, bulk tonnage oxide gold prospect. Previous widely spaced drilling at El Capitan (3 holes completed by Aurcana in 2004 and 5 holes completed by Riverside in 2008) intersected a west to north west striking, 30 to 70 meter wide zone of low grade, gold mineralization that is intermittently exposed for approximately one kilometer along a shallow dipping volcanic – sedimentary contact (the estimated dip of the contact zone is approximately 30 degrees to the south). Mineralized intervals reported by Aurcana and Riverside ranged from 40.50 meters averaging 0.215 g/t gold (CDDH 08-05) to 61.4 meters averaging 0.813 g/t (PE04-01) and included narrower, higher grade intervals ranging from 7.75 meters averaging 0.358 g/t to 9.80 meters averaging 1.067 g/t. The majority of the historic Aurcana and Riverside drill holes were spaced at 100 to 200 meter intervals and tested the central and western parts of the exposed mineralized zone, which is now referred to as the "Main Zone". A single historic hole (CDDH 08-03) located approximately 500 meters to the east of the "Main Zone" intersected 26.20 meters averaging 0.275 g/t as well as narrower intervals of higher grade mineralization suggesting potential for extensions to the south east (referred to as the SE Extension).
The preliminary geological work by Riverside showed potential for a bulk tonnage, low grade deposit however extensive in-fill drilling was required to validate the conceptual model. As announced October 12, 2011 preliminary metallurgical tests completed by Inspectorate Exploration and Mining Services supports that mineralization at El Capitan is amenable to low cost, heap leach mining.
The objective of the 2011 drill program was to validate the conceptual deposit model, increase the density of pierce points within the Main Zone and test for potential strike extensions of the Main Zone. The recently completed drilling program included 15 additional holes drilled from 9 separate stations within the area referred to as the "Main Zone". Two drill holes, CDDH 11-04 and CDDH 11-11, encountered poor ground conditions and were stopped before reaching the target zone. Drill stations were spaced at 50 to 100 meters and most of the holes were drilled at an inclination of 50 degrees along an azimuth of 30 degrees (parallel to the Riverside and Aurcana holes). Two of the 2011 drill stations were historic drill sites and three of the 2011 drill holes were vertical holes. The attached plan view map shows the location of all of the 2011 and historic holes and the following tables list all 2011 and historic results for the Main Zone.
Main Zone Drill Results
Results of the drilling program were encouraging in that the grade and thickness of mineralization encountered in the "Main Zone" showed considerable improvement over preliminary drilling results reported by Riverside in 2008. The strike length of the "Main Zone" was extended and several of the drill holes encountered mineralized intervals with potentially economic grades in excess of 70 meters in thickness including CDDH 11-07 which returned 108.35 meters averaging 0.410 g/t and CDDH 11-17 which returned 88.40 meters averaging 0.816 g/t (including 33.50 meters averaging 1.687 g/t). The widths quoted are drilled widths and are believed to represent approximate true widths. Actual widths have not yet been calculated.
Sierra Madre CEO Carl von Einsiedel, P.Geo. comments that: A total of 22 drill holes (fifteen drill holes in 2011 and seven historic drill holes) have now been completed within the Main Zone. The zone has been traced by drilling over a strike length of approximately 700 meters and appears to be open for expansion along strike to the west and north west of the area that has been tested by drilling. Only a limited amount of drilling has been completed to test the down dip extent of the known mineralized zone. In the opinion of the Company, based on the assay results from the 2011 drill holes and the reported results from the 2004 and 2008 drill holes the El Capitan target warrants additional drill testing.
Note: Gold grade reported by Inspectorate in ppb (parts per billion). The grade in g/t was calculated by dividing the reported grade in ppb by a factor of 1,000. Widths quoted are drilled width. Calculation of true widths are pending.
Note: Gold grade was originally reported by Riverside in ppb (parts per billion). The grade in g/t was calculated by dividing the reported grade in ppb by a factor of 1000. Widths quoted are drilled width. Calculation of true widths are pending.
Note: Gold grade was originally reported by Riverside in ppb (parts per billion). The grade in g/t was calculated by dividing the reported grade in ppb by a factor of 1000. Widths quoted are drilled width. Calculation of true widths are pending.
SE Extension Drill Results
In addition to the drill testing within the Main Zone a total of four drill holes (three 2011 drill holes CDDH-11-08, 11-09, 11-10, and one historic drill hole CDDH-08-03) have been completed to test strike extension of the mineralized zone to the southeast (referred to as the "South East Extension"). Although results are encouraging the gold grades and thicknesses encountered in the South East Extension are not considered to be as significant as the gold grades and thicknesses encountered in the Main Zone.
Sierra Madre CEO, Carl von Einsiedel, P.Geo. comments: "the 2011 drill results from El Capitan have confirmed there is potential for a bulk tonnage low grade gold deposit at El Capitan. The next step for Sierra Madre will be to continue the drilling program and metallurgical test work and delineate the extent of mineralization within the Main Zone. The ability to conduct year round, low cost drilling operations should make it possible for the Company to advance the project with a minimum of shareholder dilution."
QA / QC for the Sierra Madre drill program
All drill core was placed in numbered boxes and transported to Sierra Madre's secure core facilities by the drill contractor. Following detailed core logging all core was split using a diamond bladed core saw under the direct supervision of Sierra Madre's Geologic staff. One half of core was kept on site in the original core boxes, the second half was placed in labeled and sealed sample bags which were transported directly to the custody of Inspectorate America Corporation ("Inspectorate"), a laboratory certified for the provision of assays and geochemical analysis (ISO:9001-2008). Samples were transported to Inspectorate's facilities in Durango, Mexico for prep work and analyzed at their facilities in Reno, Nevada. All samples were prepared using standard industry prep methods followed by fire assay analysis and aqua regia digest for trace elements. All samples with greater than 10 g/t Au were additionally tested by fire assay with a gravimetric finish. Sierra Madre has included 4% industry certified Au standards and blanks within the sample stream in addition to field duplicates as part of the QA/QC program. Inspectorate includes a minimum of 9% certified standards and duplicate analysis as part of their laboratory procedures.
Additional gold metallic screen assays were performed on 85 select samples to check for a coarse gold component. Samples were crushed to 150 mesh and both the +150 mesh and -150 mesh portions were assayed for gold. The results show 70 of 85 samples in which 95% of the total gold is present in the -150 mesh assay. Only two samples display results where greater than 10% of total Au is present in the +150 mesh portion of the assay.
Source: www.sierramadredevelopments.com