Stock prices declined slightly Friday, turning downward near the close of the quietest session in nearly four years.

The paucity of business, which was typical of a post-Thanksgiving session on Wall Street, also stemmed from an unspecified power problem at the New York Stock Exchange that prompted a trading halt of more than an hour and a half.The Dow Jones average of 30 industrials dropped 12.13 to 2,527.23, finishing the week with a net loss of 23.02 points.

Declining issues outnumbered advances by a narrow margin in nationwide trading of New York Stock Exchange-listed stocks, with 650 up, 680 down and 559 unchanged.

Volume on the floor of the Big Board came to 63.35 million shares, down from 140.66 million Wednesday and the lightest total since a 48.86 million-share day on Dec. 26, 1986.

Most stocks declined slightly in sparse early trading before activity came to a halt on the NYSE 10 minutes after the opening bell.

The exchange resumed operations at 11:15 a.m. EST.

The pace of business had been expected to be very light anyway on what is normally one of the quietest days of the year for the financial world.

Analysts also said those traders who were present drew little inspiration from the oil markets, where prices rose sharply, and the credit markets, where interest rates edged upward.

The price of crude oil for January delivery rose about $2.35 a barrel, to just under $32 a barrel, on the New York Mercantile Exchange.

In the bond market, prices of long-term government bonds showed small losses, nudging their yields up to the 8.43 percent to 8.44 percent range.

Energy stocks managed only a mixed showing in spite of the jump in oil prices. Exxon rose 3/8 to 511/8 and Texaco gained 1/8 to 571/8, but Chevron dropped 1/4 to 681/2, and Atlantic Richfield was down 7/8 at 125.

MCA fell 31/8 to 653/8 in active trading on reports that the company was nearing agreement on a merger deal with Matsushita Electrical for a price below what some market participants had discussed.

British stocks showed gains as investors assessed the political outlook in the United Kingdom following Margaret Thatcher's departure as prime minister. British Gas rose 25/8 to 473/8 and British Telecom 15/8 to 571/8.

Nationwide, consolidated volume in NYSE-listed issues, including trades in those stocks on regional exchanges and in the over-the-counter market, totaled 80.03 million shares.

As measured by Wilshire Associates' index of more than 5,000 actively traded stocks, the market lost $5.19 billion, or 0.18 percent, in value.

The NYSE's composite index of all its listed common stocks dropped .34 to 172.39.

Standard & Poor's industrial index fell .97 to 369.71, and S&P's 500-stock composite index was down .93 at 315.10.

The NASDAQ composite index for the over-the-counter market rose .27 to 349.04. At the American Stock Exchange, the market value index closed at 295.90, up .32.