Updated from 2:16 p.m. EDT with closing stock prices

NEW YORK ( TheStreet) -- Gold prices spiked as the Federal Reserve unveiled an open-ended asset-purchase program Thursday as part of an aggressive monetary stimulus package meant to stoke improvement in the jobs market.

Gold for December delivery jumped $38.40 to settle at $1,772.10 an ounce at the Comex division of the New York Mercantile Exchange. The gold price traded as high as $1,767.20 and as low as $1,720 an ounce, while the spot price was rising $36.10, according to Kitco's gold index.

There were a number of scenarios on the table for Thursday afternoon, with the most extreme option being a massive bond-buying and mortgage buying program from the Fed -- similar to the monetary stimulus implemented after the 2008 financial crisis -- or the opposite option of the central bank punting on QE3 until its next meeting.

Ultimately, the Fed chose to announce plans to purchase $40 billion worth of mortgage-backed securities per month until it sees substantial improvement in the employment picture. It also extended Operation Twist, where it buy longer-term securities as its shorter-dated ones mature each month, until the end of the year and pushed its pledge to maintain its zero interest rate policy stance into at least mid-2015.

Silver prices for December delivery leaped $1.49 to settle at $34.78 an ounce, while the U.S. dollar index was falling 0.43% to $79.37.

Gold prices have rallied since Bernanke said he was open to the idea of a fresh round of easing at the Jackson Hole, Wyo., global economic summit last month. The yellow metal leaped again last Friday when the U.S. monthly employment report came in weaker than expected. The number confirmed Bernanke's concerns about labor market softness, and investors fled to gold as a safe haven in anticipation that more easing will eventually boost inflation.

Gold mining stocks closed mostly higher Thursday. Shares of NovaGold Resources ( NG) spiked 7%, while Yamana Gold ( AUY) rose 6%.

Among other mining stocks, Newmont Mining ( NEM - Get Report) charged up 5.5%.

SPDR Gold Trust ( GLD - Get Report) and iShares Gold Trust ( IAU - Get Report) both rose 2%.

-- Written by Joe Deaux in New York.

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