Think back to just months ago, when the biggest news in the mining and metals sector was whether BHP Billiton (NYSE:BHP) would succeed in its efforts to buy Rio Tinto (NYSE:RTP). Even then, there was a less overt discussion about whether or not the commodities produced by the two companies, especially iron ore, would stop growing in price before they crashed into the moon.

All that's changed now -- dramatically, rapidly, and possibly for years to come. Rio Tinto, for instance, is cutting production and has taken it on its proverbial chin, as copper and aluminum prices have fallen sharply. The company has already announced an 18% chop in iron ore production -- as its steelmaker customers trim their output. I wouldn't be surprised by further reductions by the company in the output of its other metals.

This week will bring us continued news -- probably unpleasant -- of the metals companies' quarterly earnings. Last week, Alcoa (NYSE:AA), the world's aluminum majordomo, announced a $1.19 billion hickey for the quarter. The primary culprits were slowdowns in transportation and construction activity, which pushed supply of the light metal far ahead of demand and affected prices accordingly.

On Wednesday, we'll hear from Freeport-McMoRan Copper & Gold (NYSE:FCX), which will likely post a loss of around $1 per share for the quarter, versus earnings of $1.36 a year ago. Amazingly, it was not that long ago when telephone lines and air-conditioning units were subject to pilfering by those with a yen for the value of the red metal contained in them. But that was before copper prices slid by more than 60%.

And as if expanding supply-demand imbalances weren't enough in both copper and aluminum, BHP last week agreed to increase the amount it pays in processing fees to Japan's Pan Pacific Copper. That's great for smelting companies, but it'll come at the expense of miners. BHP's agreement corresponds to a similar pact between Freeport and Mitsubishi Materials.

What does all this mean for Foolish investors? Ordinarily, I'd be all over buying shares of Rio Tinto, Freeport, or Brazil's big miner Vale (NYSE:RIO). But let's face it, the metals markets may still not be close to their bottoms. On that basis, let's give the group some more time and seek out more alluring sectors for our investment dollars.

Of the companies mentioned, BHP, Freeport, and Vale have been accorded five stars by Motley Fool CAPS players. Why not weigh in with your thoughts on the companies?

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Fool contributor David Lee Smith doesn't own shares in any of the companies mentioned. He does, however, welcome your questions or comments. Try any of our Foolish newsletters today, free for 30 days. The Motley Fool has a disclosure policy.