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Faster Soil Sampling for Copper-Silver Projects Using Portable XRF

by Philippine Resources - November 01, 2022

An Explorer’s Story By: Michelle Wright

A portable X-ray fluorescence (XRF) analyzer is a powerful tool to have in your mining and geochemistry field kit. One explorer uses three Vanta™ handheld XRF analyzers for copper-silver exploration in Peru. Todd Houlahan, Olympus' Director of International Mining, recently sat down with Lars Dahlenborg, President of Hannan Metals overcome challenges in exploration.

The San Martin Project: A Copper-Silver Target in a Dense Rainforest

The San Martin Project: A Copper-Silver Target in a Dense Rainforest

The top challenge Hannan Metals faces in its copper-silver exploration projects is the terrain.

Hannan Metals’ San Martin project—a strata bound sediment-hosted copper-silver target—is in the Amazon foreland basin, eastern Peru.

This region shows evidence of a basin-wide mineralization system active over hundreds of kilometers. This area is difficult to access due to dense rainforest and steep slopes. To get to the nearest field site, geologists must walk 1–3 hours from the closest 4x4 road. Another challenge is the limited outcropping.

While prospecting creek and stream sediments are effective methods to reduce the search space in this terrain, the dense vegetation and lack of rock outcrops—less than 1%—make it difficult to prove the continuity of mineralization between outcrops. As a result, Hannan Metals needs to The San Martin Project perform systematic soil sampling and analysis to map mineralization under cover.

Faster Soil Sampling for Copper-Silver Mineralization:

Hannan Metals turned to Vanta handheld XRF for faster soil sampling. To test its analytical capabilities for the project, Hannan Metals compared the Vanta XRF data to the lab data from conventional soil sampling.

The results exceeded expectations:

  • Excellent spatial correlation between the Vanta analyzer and lab data for copper (Cu)—the primary element of interest.
  • The Vanta analyzer detected the same anomalies as the lab data in the same dynamic parts per million (ppm) range.
  • Very good correlation with known outcrop mineralization.

Importantly, the Vanta analyzer produced fit-for-purpose data for key elements:

Pathfinder elements: copper (Cu), zinc (Zn), manganese (Mn), iron (Fe), arsenic (As), and nickel (Ni)

Major elements: potassium (K), calcium (Ca), magnesium (Mg), barium (Ba), silicon (Si), and titanium (Ti)

Establishing a Quality Control Program for the Copper-Silver Exploration Project:

All in all, the Vanta analyzer provides many benefits for the copper-silver project:

  • 60% faster sampling rate enables the geologists to sample a larger area and increases the chance for discovery.
  • Faster communication of results to management and other stakeholders.
  • Enables real-time decisions during soil sampling—helpful for determining infill or extension of sample traverses
  • Minimal sample size: reduces 800 kg of soil per month.
  • Good value: payback time of one Vanta analyzer is about four months at the current sampling rate (this only accounts for hard assay costs—not the other logistical benefits).

 

To learn more: TRADERS INDUSTRIAL SUPPLY CO., INC. 24th Floor Trident Tower 312 Sen. Gil Puyat Ave., Makati City 1209 Philippines E: trisco@pldtdsl.net | 1980trisco@gmail.com T: +632 8817-9004 | +632 8844-0749


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Philippine Resources - August 31, 2021

Automated, Robotic Innovations for Analyzing Geological Samples with Portable XRF

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Key to this has been their ability to test a far greater number of samples using their portable XRF analyzers than would be possible if all samples were assayed in the lab. GERDA is critical to their ability to do this. GERDA is designed to: Increase sample throughput for existing portable XRF owners Help select samples for more expensive laboratory assay Provide faster access to meaningful results for real-time follow up/infill Reduce the overall cost of exploration analytical budgets Make exploration programs more efficient To see how GERDA works with portable XRF, watch this quick video: https://www.youtube.com/watch?v=3-Gesp0Gjpk What is Nugget Effect Gold Assay (NEFFA)? To understand this new technique, it is important to know how the “nugget effect” works. The nugget effect is a term used to describe the sampling problem that can occur when there are large gold particles (nuggets) in a sample. 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Here’s how it works: Representative samples of 20–30 g, depending on the nature of material, are isolated in a medium such as a clear sample bag or under plastic film to ensure that there’s no contamination from an external agent The sample is distributed evenly over a 10 cm × 10 cm square with the depth of the material being no thicker than 2 mm A grid or matrix is placed over the sample, with individual matrices measuring 1 cm × 1 cm Measurements are performed within each square cm, and the average of all results is reported The technique is most effective on crushed rock or crushed drill core samples with a grain size 3 mm, but not on homogenized pulp samples Rotary air blast and reverse circulation (RC) samples can be analyzed directly This method takes the throughput advantages of GERDA for general exploration projects and adds additional value for gold exploration by providing gold estimates using XRF. We acknowledge this method may be considered non-traditional. 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Philippine Resources - December 07, 2021

Portable XRF for Gold (Au) and Au Pathfinders for Mineral Exploration and Ore Body Vectoring

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Philippine Resources - March 29, 2022

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