Though far from weak, the first-quarter earnings announced yesterday by Dow 30 component and aluminum heavyweight Alcoa (NYSE:AA) nonetheless missed the consensus analyst estimates. Are the "light" earnings a concern?

That depends. No less than 16 analysts cover the stock, and earnings estimates ranged from $0.38 to $0.51 a share -- hardly a consensus. And while net income from continuing operations of $0.40 per share fell a few pennies shy of the $0.42 per-share mean estimate, that's still a 79% jump year over year.

Growth was fueled in part by exploding alumina prices. This benefits miners like Alcoa, BHP Billiton (NYSE:BHP), Rio Tinto (NYSE:RTP), and Alumina Ltd. (NYSE:AWC). But alumina is also an input for Alcoa's finished products, and calculating the net effects of higher raw materials costs on Alcoa is a source of headaches for analysts and investors alike.

Alcoa's stated goal is to get the "first quintile return on capital performance" in a business that is extremely capital-intensive. To accomplish that in 2003, the company would have had to muster a return on capital (ROC) of 15.9% instead of the 7.6% reported. Still, as the company works to achieve that goal, it will positively impact future results, and an improving economy clearly benefits aluminum prices.

And perhaps now that aluminum prices have had a chance to catch up with alumina prices, analyst estimates have a better chance of hitting the target. These estimates call for earnings of $0.49 a share next quarter and $2.04 for the full year -- giving the stock a forward multiple to earnings of around 17.

Few doubt that Alcoa is a global industrial leader. For natural resource investors looking to diversify into aluminum, there's nobody in its class.

Interested in discussing mining and metals with other investors? Try the Motley Fool's Mining and Metals discussion board -- or try the many company discussion boards including Alcoa .

Fool contributor W.D. Crotty does not own stock in any of the companies mentioned.