The writedown is at odds with Rio Tinto and Northern Star commentary that inflation is easing.
Hermosa is one of two major developments South32 has in North America.
The ASX’s critical minerals producers are facing a blow-out in costs as the challenging geology of extracting green metals comes up against high prices for labour, utilities and services, destroying more than $6 billion in shareholder value.
Investors say the lack of discipline around costs will make boards reluctant to invest in projects targeted at decarbonisation at a time when the world faces a shortage of minerals essential to the energy transition.
James Thomson is senior Chanticleer columnist based in Melbourne. He was the Companies editor and editor of BRW Magazine. Connect with James on Twitter. Email James at j.thomson@afr.com
