Gold futures closed above their worst levels Thursday, but still ended the session at a six-week low with traders using strength in the U.S. dollar as an excuse to continue to lock in recent gains

Gold for August delivery finished down $15.50 at $633.50 an ounce on the New York Mercantile Exchange – its weakest closing level since April 24. It fell as low as $625.70 early in the day, a level not seen since April 20.

On Wednesday, the contract closed out the month with a loss of almost $12, its first monthly loss since February when the front-month contract lost about 2% of its value. Contributing to the decline were comments from the head of Gold Fields, who said he expects the price to correct another $100 before resuming a rise past the former historic high of $850 an ounce.

"Lest anyone had remaining doubts that gold is (also) a two-way market, this morning's implosion in the price was probably enough to do away with such uncertainty," said Jon Nadler, investment products analyst at bullion dealers Kitco.com.

The combination of a temporarily weak dollar, a steep sell-off in the copper pits and fresh round of fund liquidations have gold starting to look "as if it really wants to complete a full 50% correction from last month's highs," he said. "Such a move could indeed bring it anywhere near $585 to $600 in coming sessions."

The dollar was strong early in the session, sending gold lower, before easing back a bit following a raft of economic data showing a mixed picture of the economy. The greenback was last trading at 112.70 yen, up 0.2% on the day but off an early high of 113.35. The euro stood at $1.2792, down 0.2% on the day but comfortably above its early low of $1.2719.

Other metals prices also recovered from their worst levels, with July copper closing down 15.3 cents at $3.471 a pound after earlier being suspended limit down and hitting a one-month low of $3.34 a pound.

Dale Doelling, said investment funds may be bailing out of copper, a move he described as premature.

"The fact that it's (ended) down just a bit says we just saw a tremendous buying opportunity that may not materialize again for quite some time," he said.

July silver closed down 55 cents at $11.905 an ounce, falling below the $12 an ounce level for the first time since May 22.

July platinum ended down $17 at $1,229.80 an ounce and June palladium lost $9.85 to close at $337.40.

Peter Grandich, editor of The Grandich Letter, said today's close below $635 "could suggest a test of the psychologically important $600, but the real long-term support is in the $575 area."

"The key in the coming days and weeks is to view this as a correction in a secular bull market – not the end."

On the supply side, gold inventories were unchanged at 7.79 million troy ounces as of late Wednesday, according to Nymex data. Silver supplies fell by 255,246 troy ounces to 108.8 million and copper supplies fell by 212 short tons to 9,544 short tons.