The mint is selling about 30,000 historic $5 and $10 coins dating back to before the First World War.
They are among the country's first gold coins, struck by the mint between 1912 and 1914.
The coins are being sold by weight, with a premium added for their collectability and historical value.
The $5 coins, with about seven grams of gold, are going for $500 each, plus tax.
The $10 coins, with about 15 grams of gold, are being sold for $1,750.
Another 200,000 of the coins, which have been stored by the Bank of Canada for the past 75 years, are not considered to be of high quality and will be melted down.