Particularly after some disappointing first-quarter earnings and the accompanying 6% drop in its share price Friday, copper and molybdenum miner Taseko Mines (AMEX: TGB) is sporting a bargain valuation that warrants special Foolish consideration.

Hampered by nasty winter weather in January and February, Taseko's flagship Gibraltar mine saw a 17% year-over-year decline in copper output to stand at 19.2 million pounds. On an adjusted basis, earnings per share increased 50% to $0.06, but no matter how you slice it the company's net income of only $5.7 million came in well below the mine's potential following a $300 million phase 2 expansion project that was completed last year. Aside from the weather, Gibraltar's results were affected by the stronger Canadian dollar, higher costs for fuel and other consumables, and a bout with some relatively lower-grade material. As a result of these factors, and the lower production volume, Gibraltar's total cash costs rose 35% to $2.10 per pound.

Despite these recent challenges, I believe Taseko's 75%-owned Gibraltar mine remains a cuprous cash cow, and that a bullish long-term outlook for copper prices makes the stock's recent weakness an alluring entry point. Fools may recall that the miner's Prosperity copper and gold project was essentially stripped from the market's valuation of the shares after the Canadian government decided not to issue a permit for the mine last year. At the time, I argued that Taseko's Gibraltar stake alone justified a $4.50 share price, but that was before the company expanded the mine's reserve base by a remarkable 80% last month. Now, instead of 2.5 billion pounds, Gibraltar is expected to recover 4.3 billion pounds over the remaining life of the mine.

What's more, Taseko intends to execute a long-anticipated, $325 million phase 3 expansion of the operation that will increase annual production capacity by an additional 50% to 180 million pounds per year. With the lion's share of Taseko's portion of the price tag already raised through a $200 million offering of senior notes, I believe Taseko stands in a very enviable position with respect to production growth and likely margin expansion. Based upon Gibraltar alone, I consider the shares an alluring bargain.

The way I see it, the market is attaching virtually no value whatsoever to Taseko's transformative discovery of a world-class niobium deposit at its Aley property. All the world's niobium supply comes from just a few individual mines, and IAMGOLD's (NYSE: IAG) intention to spin out its Niobec niobium mine suggests that some consolidation of that industry may be afoot (potentially offering Taseko an opportunity to monetize the asset). As for Taseko's thwarted Prosperity gold mine, efforts to submit a revised mine proposal for consideration have been met with similarly vocal opposition to the initial proposal.

Taseko is certainly not the only copper stock getting hammered these days, with a double-digit hemorrhage by Southern Copper (NYSE: SCCO) in the wake of Peru's high-stakes presidential election offering a prime example. HudBay Minerals (NYSE: HBM) is rather fetching at these prices as well, and Ivanhoe Mines (NYSE: IVN) continues to get more interesting as construction of its world-class Oyu Tolgoi mine advances. Even Fools wishing to cast a wider net with the First Trust ISE Global Copper Index Fund (NYSE: CU) could unearth some meaningful gains over the long term. Standing apart from the pack, however, in terms of both the unmistakable deep value and timely growth potential, there stands only one: Taseko Mines.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.