• July 17, 2019

The Use and Abuse of Metal Equivalents; Mining Geology 2019 Conference

Published on July 17th, 2019

CSA Global congratulates Principal Mining Geologists, Steve Rose and Gerry Fahey on their recently accepted paper: “The Use and Abuse of Metal Equivalents” to be delivered at the Mining Geology 2019 Conference between November 25-26 2019 in Perth, Western Australia.

This year’s conference theme titled, “Mining Geology: 2020 and Beyond” will focus on the future of the industry and the impacts on mining geology and the mine value chain.

The presentation will be delivered under the following theme:

Best practice in data collection and mining geology – now and emerging

Hosted by AusIMM, the Mining Geology 2019 conference will outline practical and applied case studies, illustrating good practice and innovation, as well as illustrating new and emerging methods and technologies.

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ABSTRACT – The Use and Abuse of Metal Equivalents

Metal equivalents provide a useful and concise indication of the value of mineralisation that contains more than one valuable metal or mineral. They provide a single number that reflects the contributions of two or more assay results, providing a simpler presentation of information. This works particularly well in operating mines with well established recoveries and sales histories. Another application of metal equivalent is to present unfamiliar or minor exotic metals or minerals in terms that are more widely understood in the market – though usage can be problematic. Calculation of metal equivalent is dependent on assay data, metal/mineral pricing and metallurgical recoveries. Shortcomings in the calculation can occur when values are derived before actual metallurgical recoveries are known or using unrealistic metal prices.

When reporting Exploration Results, Mineral Resources, or Ore Reserves, for polymetallic deposits, the JORC Code 2012 Edition, Clause 50, sets out clearly the minimum reporting requirements under five bullet points and requires the following to be reported:

• individual grades for all the metals in the metal equivalent calculation
• assumed commodity prices for all the metals
• assumed metallurgical recoveries for all metals
• a clear statement that all elements have a reasonable potential to be sold
• show the calculation formula used

This paper provides a discussion of how to calculate metal equivalent values, and then shows why and where they are useful. The paper then identifies where errors can be made, distortions introduced, and lastly sets out the expectations for reporting metal equivalents using the JORC Code.


Steve Rose
Principal Mining Geologist

Steve has over 20 years’ experience in open pit and underground mining geology plus near mine and greenfields exploration. His experience extends to feasibility studies, property assessments, new mine development, Mineral Resource estimations and grade control improvement. Steve’s knowledge of structural geology, resource estimation and mine management provide a powerful mix of skills to assist our clients optimise the performance of their mines.

Gerry Fahey
Principal Mining Geologist

Gerry has more than 39 years’ experience in mining, geology, resources and project evaluation, and provides advice on feasibility studies, JORC and NI 43-101 reporting and independent geologist reports. Gerry has a strong operational background experience in senior management roles on operating mines in Australia and internationally. His operational skills can be deployed globally to deliver onsite mining dilution and operator training workshops, as well as mentoring and training for mine geologists and technicians. Gerry is a former member of the Executive of the Joint Ore Reserve Committee (JORC) and a former chairman of the AIG (Australian Institute of Geologists).


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