Inside the El Pinguico mine, there is a large stockpile of broken mineralized material, which has existed since the mine closed in 1913. The Mexican Geological Survey (CRM in 1959 and SGM in 2012) have completed historical estimates of the stockpile's size and grade. Vangold undertook a trench sampling program of the underground stockpile in 2017 with a view to validating these historical estimates using NI 43-101 sampling standards.
(Vangold cautions that the following historical estimates were made prior to the adoption of NI 43-101, do not comply with the categories of classification set out in NI 43-101 or CIM guidelines, have not been verified and should not be relied upon. Additional work is required to verify the tonnage and grade of any minerals in the underground stockpile. A “qualified person” as defined under NI 43-101 has not done sufficient work to classify these historical estimates as current mineral resources or mineral reserves and Vangold is not treating such historical estimates as current mineral resources or mineral reserves. They are shown to give the reader a full account of historic work on the property.)
In 1959 the Mexican Geological Survey or “Consejo de Recursos Minerales” (CRM), completed a topographic survey of the underground stockpiled material and completed an estimate of tonnage. Their work concluded that there are 103,415 tonnes of material and assigned an average grade of 3.2 g/t Au and 288 g/t Ag and are referred to in their report as "probable" reserves.
The volume of the stockpile was estimated using a topographic survey of the top of the pile and the volume of the workings from historical mine plans. The grade was determined through their trench sampling of the stockpile.
Also in 1959, the CRM made an estimate of in-situ vein material based on their channel sampling program at that time. They reported 4,921 tonnes with an average grade of 5.4 g/t Au and 424 g/t Ag (CRM 1959).
In 2012 the Mexican Geological Survey, now known as “Servicio Geológico Mexicano" (SGM), again completed an estimate of tonnage and grade for the same underground stockpile. SGM classified this historical estimate into 25,600 “Certified Tonnes” and 71,228 "Uncertified Tonnes." The certified tonnes were established through trenching of the stockpile, and giving their results an influence of 5m in depth. They estimated the grade of this material as 1.67 g/t Au and 166 g/t Ag. They then extrapolated an additional 71,228 tonnes to the bottom of the stockpile, and refrained from assigning an official grade to that material.
In 2017, Vangold Mining's consulting geologist and QP Carlos Cham Domínguez completed a re-sampling program on the top of the stockpile consisting of 57 samples from 20 trenches (mostly historic with a few new trenches) and returned similar grades for these trench samples as reported by SGM. The Vangold trenches were made to an average length of 6.42 meters and averaged 1.75 g/t Au and 183.5 g/t Ag. *
The results from Vangold’s January 2017 sampling program confirmed the grades found by SGM in 2012, as most of the individual assay results - and the overall average grades - are close for both gold and silver values. The results from the CRM study in 1959, however, show considerably higher gold and silver values than either SGM's or Vangold’s sampling. CRM reported average grade of 3.2 g/t Au and 288 g/t Ag. The higher results in the 60 year old CRM study may ultimately prove to be correct as the stockpile in 1959 the of the top of the stockpile may not have been so covered or diluted by occasional falls of waste rock from the walls of the open stopes as they appear today.
* “All samples were collected, recorded, bagged and sent by Vangold’s consulting geologist to ALS Laboratory in Guadalajara, Mexico for sample preparation. Gold, silver and multi-element ICP analysis was completed at the ALS laboratory in North Vancouver, Canada. Rock samples were fine crushed (70% passing a 2mm screen), pulverized (85% passing a 75 micron screen) and a pulp split separated for assaying by a riffle splitter. 30 gram portion of each sample was assayed for gold by standard fire assay and a 10 gram split was analyzed for 35 elements by ICP method. Standard reference material and blank samples were inserted into the sample stream at a 5% insertion rate with pulped samples from the underground stockpile for quality control purposes. The results of the standards and blank samples were satisfactory. All data was collected with industry standard practices and assay results were verified by Vangold’s consulting geologist.”