George T. Turner, 73, one of this country's leading philatelists who acquired what has been described as the greatest private philatelic library in existence, died Tuesday at his home in Washington after an apparent heart attack.

As curator of philately at the Smithsonian Institution from 1958 to 1962, he found his biggest job was to remount the entire National Postage Stamp Collection there for exhibit in what was then the new Museum of History and Technology.

A research chemist, Mr. Turner had retired from his profession in 1958 to devote full time to a hobby and principal avocation that dated back to his youth.

His stamp-collecting interests were diverse although he concentrated on U.S. internal revenue stamps. He built up a remarkable reference liabrary. He had an extensive collection of philatelic bookplates. He was the author and editor of numerous books, articles and journals on philately.

Mr. Turner eventually acquired more than 300 memberships in philatelic organizations around the world. He was president of the Philatelic Literature Association from 1952 to 1963.

He was a vice president of the American Philatelic Society from 1961 to 1965, and president of the SIPEX international stamp exhibition held in Washington in 1966. He had served as president of the American Philatelic Congress, was a founder of the American Academy of Philately and had been a research philatelist with the Bureau Issues Association.

Mr. Turner's honors were many. He signed the Roll of Distinguished Philatelists of the Philatelic Society of Great Britain. He received the Alfred Lichtenstein Award of the Collectors Club of New York, the Luff Award of the American Philatelic Society, and the Eugene Klein Award of the American Philatelic Congress. He was a fellow of the Royal Philatelic Society in London.

Mr. Turner was born in River Forest, Ill. He earned bachelor's and master's degrees in chemistry from Cornell University. From 1931 until coming here in 1958, he had worked as a research chemist or chief chemist for the Armstrong Cork Co., U.S. Steel, Johnson and Johnson, the Revertex Corporation of America and the I.B. Kleinert Rubber Co.

He is survived by a daughter, Marjorie T. Williams, of Barrington, Ill.; a sister, Elizabeth Turner, of Southbury, Conn., and three grandchildren. The family suggests that expressions of sympathy be in the form of contributions to the American Heart Fund.