Goldbugs will have another form in which to acquire their favorite element come September when the one-ounce Canadian gold maple leaf goes on sale. However, those eager to buy officially minted U.S. gold will have to wait until at least next June.

One million of the Canadian coins, which have a fineness of .999 and carry a face value of $50, will be produced this year. Double that number will be struck in 1980 and 1981, and thereafter according to demand. The obverse of the coin will carry an effigy of Queen Elizabeth. The country's first gold investors coin will bear the inscription, "Canada, Fine Gold, 1 oz Or Pur." The Canadian coin -- as well as all gold coins -- will sell at whatever the current spot price is for bullion, plus a premium.

The Royal Canadian Mint estimates that 40 percent of them will be absorbed by the American market. Among the dealers handling the gold maple leaf will be Merrill Lynch, Republic National Bank, Monex International Ltd. in California, and Deak-Perera in Washington.

Both the Canadian and American pieces are being minted by their respective governments in efforts to cut into soaring sales of South African krugerrands, the most popular type of gold for the average investor. In 1978, more than 3 million of the one Troy ounce gold coins were sold in the United States, triple the number of the previous year. By contrast, the amount of gold that went into domestically produced medallions and other investment type products decreased last year to 2.1 tons, from 8.6 tons in 1977.

According to Constantine Michalopoulos, a Washington gold expert, "the decline basically reflects the availability of better investment alternatives for gold than the privately minted medallions whose price usually includes a considerable mark-up over their gold content." The mark-up or premium on krugerrands varies between 4.5 and 8 percent depending on the quantity purchased. The maple leaf premium has not been set yet, although the Financial Post of Toronto said recently it had heard the premium could go as high as 7 or 8 percent.

A gold expert a Deak-Perera predicted krugerrand sales would not be affected by the maple leaf. Its higher premium and limited edition make it a semi-numismatic coin, "one people will buy and sit on, not trade," he said.

He was even less sanguine about the chances of the American gold piece supplanting the krugerrand, an idea of those who conceived it. Its origins were as much chauvinistic -- foreign banks were buying up America's gold -- and political some Americans dislike supporting South Africa -- as financial. Its form will not prove competitive in the investment world, say dealers.

Gold coins have not been minted in the United States since the 1930s so the U.S. Treasury, which is adamantly opposed to remonetizing the metal, lobbied against the striking of a new gold coin. The result is a medallion commemorating outstanding American contributors to the arts. (Ironically the new medallions will be made from the melted down coins.) At least one million are scheduled to be minted in the fiscal year beginning in October, and 1.5 million annually for four more years, although Congress has yet to pass a supplemental appropriation of $10 million to begin production and promotion.

The first two medallions, honoring Grant Wood and Marian Anderson, will weigh one ounce and one half Troy ounce, respectively, and sell for a premium of not more than 3 percent over the spot price of gold bars. Production is under the supervision of the U.S. Mint (although it may be contracted out). It is not expected that the medallion will carry any of the slogans of U.S. currency.

"Everybody wants it to be a coin," said Margot Russell of Coin World magazine. An official coin of the realm commands world respect, she continued. "A medallion is second best."

As dim as seem the U.S. gold piece's prospects for competing with the drugerrand, which is legal tender in South Africa and continually minted in large quantities, the medallion;s prospects for appreciation seem good, according to Russell. The medallion will be marketed not through dealers but directly by the Treasury, which has a mailing list of 3 million coin collectors. Chances are strong that the first will be snapped up quickly by the public and that a secondary market will soon develop.