Teams of FBI agents and Washington-area police staged simultaneous raids on eight separate locations yesterday as authorities announced they had uncovered the region's largest silver and gold fencing operation.

Sixteen people were named in arrest warrants issued as a result of the eight-month FBI and D.C. police undercover investigation, dubbed "Operation Greenthumb." Investigators said two gold and silver dealers, Alan D. Danneman, 32, and Joseph G. Martin, 36, allegedly used their businesses as "fronts" to purchase stolen jewels and silverware from burglars who had broken into hundreds of homes.

FBI officials estimated that Danneman and Martin allegedly bought about $3 million in stolen gold and silver in the last year, much of it at 10 percent of its current market value. The stolen items were largely sold to Danneman's business, ADE Inc. at 1411 K St. NW, and Martin's firm, Royal Carpet and Tile Co. at 1785 Florida Ave. NW, the officials said.

"These are the two major fences in the metropolitan area," declared Theodore M. Gardner, the special agent in charge of the FBI's Washington field office. "Taking them out of action will have a very definite beneficial effect in reducing the burglary rate" in the area.

Agents last night recovered about $25,000 in cash, including 12,000 silver dolalrs, during a search of Martin's residence at 14718 Claude Ave., Colesville, officials said.

FBI agents and local law enforcement officials searching the homes and businesses of suspects also reported finding drawers full of diamond jewelry, lists of bank accounts and a paper bag containing college rings and gold medallions that was hidden behind a false wall panel. They also found quantities of gold and silver chalices, watches, earrings, tea sets, antiques, goblets and other precious items. "It will be days before we can come up with a dollar amount" on the seized goods, according to Thomas Baker, a senior FBI agent.

Law enforcement officials said that the burglars, after breaking into homes throughout the metropolitan area, brought stolen merchandise to the two stores.

Couriers would often transport untraceable stolen items to commercial smelters in New York, Houston and around the Washington area, according to sources. In some instances, couriers checked suitcases full of stolen items aboard shuttle flights to New York, sources said.

The alleged fences made sizable profits in the resale of the goods, officials said. For example, smelter operators who bought the stolen items paid close to the full market value for thousands of dollard worth of merchandise that the alleged fences had bought for only a few hundred dollars, sources said. In one case, Martin allegedly paid a suspected burglar $850 for silverware that was actually worth $15,000, according to the FBI.

Gardner and D.C. Police Chief Burtell M. Jefferson announced the investigation at a joint news conference at the FBI's Washington field office.

They said 12 of the 16 people named in the warrants were arrested yesterday on charges relating to the fencing operation, including conspiracy, interstate transportation of stolen property and embezzlement. Martin and Danneman were among those arrested yesterday, and they were charged with interstate transportation of stolen property.

Gardner said 70 suspected burglars have been identified in the investigation and police have solved more than 200 burglaries of homes in Washington and the Maryland and Northern Virginia suburbs. Gardner said he expects the number of burglaries solved as a result of the investigation to increase sharply now that the probe has been made public.

"We feel this is the most significant investigation of fences in this area in the last 10 years," Gardner said. The probe began last September after burglary suspects told investigators how stolen goods were being disposed of.

Jefferson noted that the District's burglary rate soared in the last half of 1980 and he attributed "a great deal" of that to the rising gold and silver prices that made the theft of jewelry and silverware increasingly attractive to burglars.

Officilas said that "Greenthumb" -- coined because FBI official Gardner was plowing what was regarded as fertile ground -- is the first major undercover operation here aimed at catching fences. They are people who buy stolen merchandise from burglars and thieves and resell it for a profit.

The investigation is also a significant departure from the much publicized undercover "Sting Operation," in which undercover investigators posed as fences and bought stolen merchandise from thieves. The "sting" technique, which was copied many times by police departments across the country after it was unveiled here five years ago, concentrated on capturing the petty thieves who stole goods and armed robberies, muggings, office thefts and burglaries.

Law enforcement officials have long said that fences are among those most responsivle for thefts, especially burglaries, because they provide a ready merchandise outlet for thieves. Investigators said "Operation Greenthumb" revealed that nearly all of the burglars selling to the fences were drug addicts seeking cash in order to buy more drugs.

During the probe, one FBI agent posing as a free-wheeling jewelry expert worked for more than four months as a manager at Danneman's K Street business. Wearing gold chains and driving a flashy car, the undercover agent got the job after making contacts at a gold and silver show, according to sources familiar with the investigation. He quickly gained their confidence and a short time later went to work for Danneman, while wearing a hidden recording device.

Meanwhile, agents broke into Martin's precious metals store in the middle of the night and hid a microphone under the counter, which was used to pick up conversations in the store between store employes and suspected burglars peddling stolen merchandise. Investigators also benefited from a wiretap on the store's telephones.

Both the hidden microphone and the telephone tap were installed after law enforcement officials received authorization from U.S. District Court Judge Norma Holloway Johnson.

In addition to Martin's home, agents and local police searched Martin's Florida Avenue store, another store he operates under the name of Montgomery Gold and Silver at 18115 Georgia Ave., Olney, as well as Danneman's K Street business and his home at 9610 Franklin Ave., Lanham.

The other searches were conducted at Daube's Jewelry at 1243 W. Broad St., Falls Church, which was operated by another man arrested yesterday, Robert O. Daube of 2210 McLean Park Rd., Falls Church. Daube allegedly received stolen merchandise from Danneman, the FBI said. The residence of two men who the FBI alleged were lieutenants in the operation also were searched.