Investing Fools should keep two parts of the natural resource sector within their sights. In energy, skyrocketing crude prices could lead to all manner of intrigue going forward.

And in metals and mining, just as in oil and gas, heightened demand in developing nations translates to higher prices, along with rapid consolidation.

We'll focus today's camera for the sector on Vale (NYSE:RIO), the big, Brazilian-based miner that's a force -- with BHP Billiton (NYSE:BHP) and Rio Tinto (NYSE:RTP) -- in iron ore and nickel. Iron has been in especially high demand worldwide as key to steel production.

But now, after unsuccessful efforts to pick off Anglo-Swiss mining group Xstrata, Vale is set to raise up to $15 billion, intending to return to the acquisition trail and add to its product quiver. Targets could include U.K.-based Anglo American PLC; copper, gold, and molybdenum producer Freeport-McMoRan (NYSE:FCX); and Alcoa (NYSE:AA).

Not long ago, I told my Foolish friends that Freeport might draw acquisition attention from one of several companies, including Vale. So interest from Rio de Janeiro in the Phoenix-based company wouldn't be surprising, especially since Vale recently opened a copper mine in the northern Brazilian state of Para.

In fact, I'll crawl out on a limb and offer that Freeport is a more likely target than Anglo American or Alcoa -- even though Vale is now involved in the production of alumina. It appears that copper creates a brighter gleam in Vale's eye than aluminum does, and buying Anglo, which produces diamonds and precious metals, could set Vale back as much as $120 billion.

I view this intriguing set of circumstances through a couple of investment prisms: First, while Freeport's share price has improved more than 50% in the past year, I wouldn't sell the company short -- or sell it at all, for that matter. Despite its run-up, it still trades at a low forward multiple, produces an important trio of products, and could end up as someone's acquisition target, if not Vale's.

As to Vale itself, the company is rapidly becoming a bigger force in metals and mining. Given the world's increasingly voracious appetite for Vale's wares, I'm labeling it a company that should not be ignored.

For rust-proof Foolishness: