NEW YORK ( TheStreet) -- Freeport McMoRan ( FCX), the copper-mining giant, suffered a difficult conclusion to its second quarter as copper prices weakened sharply, but the company's results, scheduled for release Wednesday morning, won't matter nearly as much as evidence that the metal stands to reverse a months-long negative trend -- as it did on Tuesday.On the London Metals Exchange or the New York Mercantile Exchange, where copper prices had been plunging since the spring, the metal jumped by more than 2% Tuesday. That sent Freeport's New York-listed stock flying. (It had declined by more than 30% since April.) In recent trades, shares of the Phoenix-based miner, the world's largest publicly traded copper extractor, were moving at $64.78, up 6.4%, albeit on lighter-than-average volumes. In the second quarter, however, the LME spot price for copper averaged $3.18 a pound, down substantially from the $3.42 the metal fetched in the first period of the year, when soaring prices allowed Freeport to exceed forecasts and post robust year-over-year comparisons. Wall Street analysts have spent July cutting their estimates for the company's first-quarter and full-year profit. The weakening value of copper has largely been due to China's well-documented efforts to ease back on its torrid economic growth. As a result, copper imports into China have declined of late. On July 8, for example, Anthony Rizzuto, equities analyst with Dahlman Rose in New York, slashed his earnings estimates for Freeport's second quarter to $1.30 from $1.75. Rizzuto now believes that copper prices will average $3.18 a pound for the rest of the year. That's sharply below Freeport's own earlier in-house view that prices would average $3.50 for the year. As a group, analysts are now expecting Freeport to earn $1.31 a share during the period on revenue of $3.56 billion. When the company reported first-quarter results in April, executives felt confident enough in global demand for industrial metals to detail a robust plan to restart moth-balled mining projects in the U.S., with $1.7 billion in capital expenditures planned for 2010. Metals and mining shares surged across the board Tuesday. The big three of BHP Billiton ( BHP), Vale ( VALE) and Rio Tinto ( RTP) were gaining 4.8%, 6.8% and 5.8%, respectively. Canada's Teck Resources ( TCK) was up 5%, while U.S. iron ore producer Cliffs Natural Resources ( CLF) surged 8.3%, gaining momentum late in the day. -- Written by Scott Eden in New York Follow TheStreet.com on Twitter and become a fan on Facebook.