The biggest, heaviest, inherently the world's most valuable gold bullion coin -- worth an estimated $60,777,102 at current prices -- has been unveiled by The Perth Mint, a spokesman said Wednesday.

Weighing one metric tons of 99.99 percent pure gold, the monumental coin measures nearly 80cms wide (31.5 inches) and more than 12cms deep (nearly five inches).

The coin is the pinnacle of ingenuity and innovation for which The Perth Mint is renowned.

To cast and handcraft a coin of this size and weight was an incredible challenge, one which few other mints would not even consider, said Ed Harbuz, CEO of The Perth Mint.

The one metric ton coin features a bounding red kangaroo surrounded by stylized rays of sunlight and bordered by the inscription AUSTRALIAN KANGAROO 1 TONNE 9999 GOLD and the year-date 2012.

Issued as Australian legal tender, the obverse of the coin features the Ian Rank-Broadley effigy of Queen Elizabeth II, accompanied by the inscriptions ELIZABETH II, AUSTRALIA and the monetary denomination of 1 MILLION DOLLARS.