43-101 2007 Technical Report On The San Antonio Project, Baja ...

Derry, Michener, Booth & Wahl Consultants Ltd. Page 3914.0 DATA VERIFICATION14.1 IntroductionDue to the nature of RC sampling, one control sample (i.e. Duplicate, Standard or Blank) issystematically and alternately inserted every 10 samples by the exploration geologists.The sequence is: every tenth rig sample, (i.e. 15.2 m,) – Standard, every twentieth sample(30.4 m) – Blank, every thirtieth sample (45.6m) – Duplicate, every fortieth sample (60.8m.) –Standard, etc. This sequence is repeated continuously from surface collar to the end of each hole.Thus each mineralized interval, normally >30 m, is backed up by 2 to 3 of these QC checks. Inthe case of deep holes there is normally a thick barren section near surface, so that it is possiblethat some of this material can be set aside for assaying at a later date, thus reducing assay andreference material costs.As mentioned before, duplicates are obtained using the two 25% samples from the lateraldischarge of the drill, and packed in two pre-numbered plastic bags.In general, the reference material (i.e. Standards and Blanks) consist of pulverized materialobtained from “RockLabs Limited” in New Zealand. Standards utilized within the reversecirculation sampling consist of Sulphide and Oxide materials with different certified Au contentvalues.After Geochemistry results are generated and certified by ALS Chemex, a statistical and/orgraphic QA/QC analyses are applied to all control samples as shown below.14.2 DuplicatesDuplicate samples are evaluated by the Spearman Rank’s correlation coefficient (R 2 ), whichconsiders differences in Au-values sorting-ranks and is calculated to assure a good positivecorrelationrepresented by the proximity of R 2 to 1. As shown in the scatter plot the Spearmanrank of 0.953 shows excellent correlation (Fig. 14.2).14.3 StandardsCertificates of results for all reference material are issued by RockLabs, these documents containmainly the mean Au values and the Standard Deviation for each standard they manufacture, andthis information is taken into account to establish the tolerance limits which determine if a reassayis required.Reference material’s results that Pitalla receives from ALS Chemex are graphically analyzed aspart of the QA/QC procedures.The RockLabs standards that have been used in the current drilling program are one sulphidetypewith code SG31, a mean Au value of 0.996 ppm and a standard deviation of 0.028 ppm; aswell as three oxide-type materials with codes OxC58, OxD43, and OxD57, and mean Au values