04 March 2025

It is with deep sadness that we announce the passing of John T. Postle, a distinguished mining engineer whose contributions have profoundly shaped the global mining industry. Born in Kirkland Lake, Ontario, Mr. Postle's career was marked by exceptional expertise, unwavering dedication, and a commitment to setting the highest standards.

Postle earned a B.Sc. in mining engineering from the University of British Columbia (1965) and a master’s degree in earth sciences from Stanford University (1968), laying the foundation for his career. He gained experience in open-pit and underground operations while working for mining companies Cominco and Falconbridge.

In 1985, Postle co-founded Roscoe Postle Associates Inc. (RPA), a consultancy that became a titan in the mining industry. Under his and William Roscoe’s leadership, RPA flourished, growing into a nationally and internationally recognized geological and mining consulting firm. His commitment to professional and ethical standards made RPA the go-to firm for resource/reserve estimates and audits, technical due diligence, and mining valuations.

One of his most significant contributions was his pivotal role in developing the CIM Definition Standards on Mineral Resources and Reserves (CIM Definition Standards), which became part of the globally recognized Canadian National Instrument 43-101. His influence extended to the international stage through CRIRSCO, where he helped define international reserve/resource standards.

Throughout his career, Postle was recognized for his outstanding contributions, including being awarded a CIM Fellowship, named a CIM Distinguished Lecturer, and receiving the CIM Robert Elver Mineral Economics Award. He was also awarded the Queen Elizabeth II Diamond Jubilee Medal for his service to the mining industry and jointly received a PDAC Special Achievement award.

His work at RPA, now part of SLR Consulting Ltd., has set the gold standard in geological and mining engineering consulting, mineral valuations, and resource/reserve work.

His profound impact on consulting, standards development, and the broader mining industry will continue to shape its future for generations. He will be remembered for his legacy of excellence and dedication.

He will be deeply missed by his colleagues, friends, and the entire mining community. Our thoughts and deepest condolences are with his family during this difficult time.