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Sombrero Age Dating, 2019
A total of seven samples of magmatic rocks were collected for U-Pb zircon geochronology analysis. From those, two samples (referred to above as A and B) were sent to Geolab SHRIMP IIe, Institute of Geochemistry – University of Sao Paulo, Brazil. They were analysed through the “Sensitive High Resolution Ion Microprobe IIe” method, or SHRIMP. The other five samples (C, D, E, F, and G) were sent to CODES Analytical Laboratory, University of Tasmania, Australia, where it was found that only three contained zircon. Those three samples were then analysed with an ASI RESOLution S-155 ablation system with a Coherent Compex Pro 110 Ar-F excimer laser.
- Porphyry-Style Alteration and Mineralization of the Middle Eocene to Early Oligocene Andahuaylas-Yauri Belt, Cuzco Region, Peru, Economic Geology, Vol. 98, 2003. Pg 1575-1605
Rocks 2018-2019 (Sombrero, Peru)
Approximately 2-3kg of material was collected for analysis and sent to ALS Lab in Lima, Peru for preparation and analysis. All samples are assayed using 30g nominal weight fire assay with ICP finish (Au-ICP21) and multi-element four acid digest ICP-AES/ICP-MS method (ME-MS61). Where ICP21 results were > 3 g/t Au the assays were repeated with 30g nominal weight fire assay with gravimetric finish (Au-GRA21). Where MS61 results were greater or near 10000 ppm Cu, 10000ppm Pb or 100ppm Ag the assays were repeated with ore grade four acid digest method (Cu-OG62). QA/QC programs for 2018/2019 rock samples using lab duplicates, standards and blanks indicate good accuracy and precision in a large majority of standards assayed. These samples were collected in a non-representative manner. The mineralization may not be reflective of the underlying system.
Channel Sampling 2019 (Sombrero, Peru)
Analytical samples were taken from each 2-meter interval of trench floor resulting in approximately 2-3kg of rock chips material per sample. Collected samples were sent to ALS Lab in Lima, Peru for preparation and analysis. All samples are assayed using 30g nominal weight fire assay with atomic absorption finish (Au-AA25) and multi-element four acid digest ICP-AES/ICP-MS method (ME-MS61). Where MS61 results were greater or near 10,000 ppm Cu, Zn or Pb the assay was repeated with ore grade four acid digest method (OG62). QA/QC programs for 2019 trench grab samples using internal standard and blank samples; field and lab duplicates indicate good overall accuracy and precision.
Intervals were calculated using a minimum of a 0.1% Cu cut-off at beginning and end of the interval and allowing for no more than five consecutive meters of less than 0.1% Cu with a minimum length of the resulting composite of 6m.
Historical Fierrazo Diamond Drill Hole (DDH) Re-Sampling 2019 (Sombrero)
Sample intervals averaged 2 meters where historical sample intervals taken and otherwise were 2 meters. Where at least half of HQ diameter core was present it was sawed into equal parts on site. Otherwise historical crush rejects were used in lieu of the core. In total 481 quarter core, 20 half core, and 10 crush rejects, approximately 3-5kg each, were sent to ALS Lab in Lima, Peru for preparation and analysis. All samples were assayed using 30g nominal weight fire assay with atomic absorption finish (Au-AA25) and multi-element four acid digest ICP-AES/ICP-MS method (ME-MS61). Where MS61 results were near or greater than 10,000 ppm Cu the assays were repeated with ore grade four acid digest method (OG62). QA/QC programs using internal standard samples, field and lab duplicates and blanks indicate good accuracy and precision in a large majority of standards assayed.
Intervals were calculated using a minimum of a 0.1% Cu cut-off at beginning and end of the interval and allowing for no more than six consecutive meters of less than 0.1% Cu with a minimum length of the resulting composite of 5 meters.
Copper and gold equivalent grades (CuEq and AuEq) were calculated using gold price of US$1,300/oz and copper price of US$3.00/lb.