George Powell displays the treasures of his nearly two-decade-old passion in every corner of his home. Track lighting accents display cases full of fossils that make one corner of his one-bedroom basement apartment look like a museum. Behind smudge-free glass are rows upon rows of shark teeth, some large, some tiny, but all polished and neatly labeled--and all unearthed by Powell.

Powell, 51, has been a letter carrier in Falls Church since 1966, shortly after his return from Vietnam, where he served as a machinist in the Navy. His co-workers at the post office all know about his avocation.

"He really enjoys his hobby," said Joe Quinones, postmaster of the Falls Church post office. "His vacations are geared around digging."

Last weekend, Powell traveled to North Carolina, chasing his dream, on a dig. His wife, Linda, calls it "playing in the dirt."

In 1980, while fishing with a friend, Powell found some fossils. They abandoned their rods and reels and began to concentrate on the mysterious rocks drifting onto the shores of the Potomac River some 100 miles south of Washington.

A few months later, Powell returned without his fishing gear, his sole purpose to root around for interesting fossils. "I could go fishing any time. I wanted to collect fossils," he said, laughing. "I found a five-inch shark tooth, and I've been hooked ever since."

In 1992, Powell made what he considers the discovery of a lifetime. While fossil hunting in a phosphate mine in Aurora, N.C., he uncovered massive quantities of teeth from an extremely rare species of shark.

"There are only a handful of teeth from this species found anywhere in the world in a year's time," Powell said. Powell immediately called Brett Kent, an instructor at the University of Maryland, to assist him with the find.

After some 14 visits to the mine over nearly two years, Powell and Kent uncovered 114 teeth from the same species. Powell said he was offered money for the teeth but chose to give them to the Smithsonian Institution in 1996 to share them with the public.

Kent helped Powell reconstruct the shark's dentition and research and write a paper that will be published this fall in Mosasaur, a fossil journal published by the Academy of Natural Sciences in Philadelphia.

"It's only the fourth set of teeth known for this shark," Kent said. "It's the first one from the Atlantic, and it's by far the largest. The second largest has 44 teeth."

Robert W. Purdy, fossil fish specialist at the Smithsonian, also has studied Powell's find, calling it "very important scientifically." The teeth, each about 2 1/2 inches long, were used to determine that the extinct shark was about 25 feet long.

"George is an exceptional collector," Kent said. "He has a very good sense of the scientific value of fossils. He's very intelligent; he learns things very quickly. He's very good to work with in the field. He doesn't get discouraged."

Dave Bohaska, fossil marine animals specialist at the Smithsonian, worked with Powell on fragments of a rare walrus skull he found. Researchers still are trying to determine if it is a new species, but Bohaska said he believes it probably already has been named. If it hasn't, Powell could achieve the dream of all fossil collectors--to name a species.

"He's done enough that he deserves it, but that's not for me to say," Bohaska said.

Three years ago, Powell donated some of his finds to his old high school, George Mason Senior High School in Falls Church. The principal arranged for a permanent display, and Powell set to work mounting and labeling his fossils for the students.

Powell, who was born and raised in Falls Church, dropped out of George Mason at 16.

On his 17th birthday, he joined the Navy because a neighbor had told Powell it helped the neighbor "grow up." He returned to the city in 1966, itching to join the fire department. With no openings, he joined the volunteer fire department and began working odd jobs until he applied to the U.S. Postal Service.

Powell has accomplished everything in his life without a high school diploma. "When I came back from the Navy, my friends were still in school, just graduating. I always regretted that."

At 32, Powell got his GED diploma. Still, he said, he always had felt like a quitter.

"I gave up on myself," Powell said.

Because of his success in paleontology, Powell often is invited to speak to students. "I've always told them to stay in school, study hard and not give up on themselves, especially when everybody else has," he said.

The walls in his apartment are coated with framed mementos from his life's pursuits. From his quarter-century in the Falls Church volunteer fire department, Powell displays pins for each rank he held. From his tour of duty in the Navy in Vietnam, his medals perch above his shark teeth. Powell said the medals are nothing, "just the medals they gave everyone in Vietnam. I'm no hero."

Powell also displays the numerous patches he designed for various Falls Church organizations, including the police department, all of which are in use today. On the wall facing his shrine to paleontology, Powell has various fish he caught in waters near Washington, mounted on driftwood and artistically arranged.

Powell is proud of his accomplishments, but one stands out above all others. In June, he was invited to the commencement ceremony at George Mason. Waiting in a room off the auditorium were his mother, sisters, friends, wife and daughter. Powell was called up to receive his honorary high school diploma, 33 years after his classmates graduated.

"You can see what I've achieved," Powell said. "Just because you fail at one thing doesn't mean you can't excel at another." CAPTION: Letter carrier George Powell, who has been collecting fossils for about two decades, displays some at his Falls church apartment. Most are shark teeth. ec CAPTION: At left, Powell holds fossils of shark teeth. His biggest find is 114 teeth from a rare species of shark, which he found in a phosphate mine in Aurora, N.C. He gave those to the Smithsonian Institution. Above, he inspects a tooth. ec