Humann was unable to preside over Mincor's annual general meeting a fortnight ago due to illness.
He joined Mincor in 1999 as its founding chairman and has overseen its transition to nickel producer and its current focus on gold.
Mincor managing director Peter Muccilli expressed his condolences to Humann's family and friends on behalf of the company.
"The sudden passing of David is a great shock and tragic loss to the Australian business community," Muccilli said.
"His incredible warmth, knowledge and dry sense of humour will be sorely missed by everyone at Mincor."
Humann, a chartered accountant, was chairman and senior partner of Price Waterhouse (Hong Kong and China firm) from 1986 until 1995, and was the managing partner of Price Waterhouse, Asia Pacific region, and a member of the world board of Price Waterhouse and of the global firm's world executive management committee.
Humann was also a director of collapsed copper miner India Resources and Skin Elements.
Mincor's board will elect an interim chairman at its next meeting in December, and will consider the appointment of a replacement director in due course.
*Kristie Batten is editor of www.miningnews.net