He attributed gold's latest rally to "heavy speculative buying ahead of the three-and-a-half-day holiday." Metals trading on the New York Mercantile Exchange closed early ahead of Martin Luther King's Day Monday. Regular trading will resume on Tuesday.

Gold for February delivery traded as high as $558.80 an ounce on Friday. The contract closed up $7.70 at $557, thereby finishing nearly 2.9% above the week-ago close of $541.20.

"There should be no doubt that gold remains in a secular bull market," said Peter Grandich, editor of the Grandich letter.

"The classic trading pattern of sustained rallies, followed by brief periods of profit-taking, which are then followed by an explosive move to the upside that squeezes the shorts badly, has happened yet again," he added, noting that gold reaching the $600 level "is a question of when, not if."

'One-sided' tug of war

The "tug of war in gold's price rope is [almost] one-sided," said Jon Nadler, an investment products analyst at bullion dealers Kitco.com, with even those who are letting go of some gold at current prices "not bailing out completely."

"There are too many factors present in the current fundamentals, and too many developing stories that will affect gold in coming months for participants to afford ignoring," he elaborated, including the resumption of nuclear research in Iran and some Asian countries diverting assets away from the dollar.

For the short run, prices may see a "possible assault on $560 on the top side," Nadler added.

Looking ahead, "on occasion, the party will look an awfully lot like it has come to an end, but these will be mere ripples in the tsunami that is the overall uptrend," he said.

Other metals took their cue from gold's rally to close the Nymex trading week.

March silver closed up 10.5 cents at $9.165 an ounce, down fractionally for the week, and March copper climbed to $2.1125 a pound, gaining 2.5 cents to end the week 1.3% higher. Prices tapped a record of $2.125 earlier.

April platinum closed up $13.60 at $1,043.60 an ounce to mark its highest level since 1980. Prices closed at $1,004.60 a week ago, and so were up 3.9%.

March palladium added $7.25 to close at $283.85 an ounce, ending the week with a $10.45 gain.

On the supply side, copper inventories were unchanged late Wednesday at 7,762 short tons, according to Nymex. Gold inventories were at 7.02 million troy ounces, up 9,116 troy ounces, while silver lost 582,204 troy ounces to stand at 120 million.