Here's something to give a fresh shot in the arm to copper, the second-best-performing base metal over the past three months: the prospect of strike action at its biggest pit.
Management at BHP Billiton-run Escondida in Chile have rejected union demands for a 7 per cent pay rise and 25 million peso ($50,104) bonus, and talks are ongoing ahead of a vote by workers on a final proposal on January 24, Bloomberg News reported on Wednesday.
As this Gadfly column argued in September, the risk of industrial action is one of the major supply-side factors supporting copper at the moment.
Escondida accounted for about 1.2 million metric tons of mined copper in 2015, so any stoppage could sharply tighten a market that Bloomberg Intelligence estimates will see a 453,000-ton surplus this year.
It's worth stepping back, though, and considering that the more feisty attitude Chile's copper miners have shown of late isn't simply a spot of local trouble. Instead, it's a symptom of factors that touch every corner of the commodity market, and ultimately play a part in rebalancing global prices.
Labour, quite as much as diesel oil, dump trucks and conveyor belts, is an essential input to any mining operation.
When commodity prices rise, miners do their utmost to expand production as quickly as possible, creating more demand for workers and machinery, and driving up prices wherever supply is unable to respond quickly enough. When prices fall, employees, as much as machinery and fuel, are liable to get laid off.
When the mining boom was at its height, high-school dropouts were able to command $268,720-a-year pay packets - more than then-US Federal Reserve chairman Ben Bernanke - to work in Australian pits. Mining employment in the country nearly doubled over the five years to 2012.
That sort of gold rush couldn't last forever, and sure enough, prices subsequently fell, giving miners the justification they needed to trim bloated workforces and get rid of their most well-paid employees.
In the four years since 2012, Australian mining employment fell by about a fifth, to the point that the entire industry now employs barely more people than Wesfarmers, the nation's biggest retailer.
Big miners have played their part. Helped by the spinoff of South32, BHP has shed nearly half its staff since 2013, going from 49,496 workers to 26,827 over its four most recent fiscal years. Rio Tinto Group dropped some 16,000 people from its payroll over the equivalent period, while Vale's loss numbers 11,205.
In all, the big three have got rid of close to a quarter of their combined labour force over the past four years - and wages, benefits and pensions, as a proportion of operating expenses, have plunged as a result.
There are long-term factors that may make this process different in future, such as the spread of automated trucks, drills and trains that are increasingly replacing human labour in the massive iron-ore mines of north-western Australia. But automation is hardly a new development in mining - we're already more than two centuries on from the time when the world's first railway journey was used to haul iron around South Wales.
Much though management and shareholders would no doubt like to keep wage bills under control, it's probable that over time, the pendulum will swing back from capital toward labour, ultimately driving up cash costs and setting the next great commodity cycle in train.
Higher commodity prices play their part in this process: those Chilean miners' 7 per cent pay demand doesn't seem quite so much when you consider that copper prices are up 31 per cent over the past 12 months.
Mine managers trying to fight the latest round of wage demands should bear that in mind. While they strive to get the best price for their minerals, union bosses are bidding up the value of their labour. The commodity cycle giveth, and the commodity cycle taketh away.
Bloomberg
This column does not necessarily reflect the opinion of Bloomberg and its owners.