Proof Coin - 1 Penny, Australia, 1930, reverse.
Source: Museum Victoria
The establishment of the Sydney Mint as a Branch of the Royal Mint in 1855 set a precedent for Melbourne to follow, however, the British government back in London would first need to be convinced of the need for a second Australian branch. The quantity of gold that was discovered in Victoria made a strong enough case for the proposal that a second mint was authorized and the first coins were struck in Melbourne in 1872.

Sovereign, Victoria, Australia, 1872, reverse.
Source: Museum Victoria

Sovereign, Victoria, Australia, 1872, obverse.
Source: Museum Victoria
Like Sydney, the Melbourne Mint was to be fully paid for by the colonial government. This included the cost of purchasing the dies used to strike the gold coins from the Royal Mint in London. Unlike Sydney, Melbourne was authorized from the start to strike full British sovereign and half sovereign denominations, but with the mint mark M to designate their Melbourne production. Dies were shipped from London bearing the date 1871 but were never used as the mint was not ready. The shipment of 1872 dies however was partly lost when the ship carrying them, the P & O steamship Rangoon, sank leaving Sri Lanka. Fortunately, the Sydney based silversmith and die sinker Julius Hogarth was looking for work in Melbourne at the time, so he was employed by the Melbourne Branch to change the last numeral of the 1871 dies to 1872 to make up for the loss of the dies. In some cases his change of date did not succeed and coins were made with the original numeral 1 visible beneath the final 2 of the date. Coins like this are called ‘overdates’.

Sovereign 1872/1 overdate.
Source: Museum Victoria
Hogarth also prepared a die for a half sovereign which was used to strike a specimen to send to London for the British government’s approval of local die manufacture, but it was rejected immediately. Unfortunately, the specimen was not retained by the Royal Mint in its collection and no example now exists.
Both Melbourne and Sydney Mints had the freedom to choose the design of their sovereigns. Dies were supplied to them with the reverse side (the side of the coin opposite the side side bearing the principle stamp or design) depicting a scene of St George and the dragon. Other dies supplied depicted a shield on the reverse side. Both mints struck coins with a shield on the reverse side, as these coins were preferred by the Indian gold traders. It has been suggested that one reason for this preference was that the Indians thought that the humiliating position of the dragon (being killed by St George) might offend their Chinese customers for whom the dragon was held in high esteem.

Proof Coin - Sovereign, Victoria, Australia, 1883, St George reverse.
Source: Museum Victoria

Proof Coin - Sovereign, Victoria, Australia, 1883, shield reverse.
Source: Museum Victoria
The Melbourne branch of the Royal Mint continued to strike gold coins until 1931.

Proof Coin - Sovereign, Australia, 1931, obverse, one of the last sovereigns struck at the Melbourne Mint.
Source: Museum Victoria

Proof Coin - Sovereign, Australia, 1931, reverse, one of the last sovereigns struck at the Melbourne Mint.
Source: Museum Victoria
The order for dies dated 1932 was rejected for all branch mints, as was a special request for sovereign dies dated 1934 to make a coin to commemorate the Victorian Centenary. Instead, a special silver coin was struck for that commemoration.

Pattern Coin - Florin (2 Shillings), Centenary of Victoria & Melbourne, Trial Strike, Victoria, Australia, 1934-1935, obverse.
Source: Museum Victoria

Pattern Coin - Florin (2 Shillings), Centenary of Victoria & Melbourne, Trial Strike, Victoria, Australia, 1934-1935, reverse.
Source: Museum Victoria
In 1916, Australian coins were being made in London, and when dangers to shipping due to the war threatened the supply of these coins to Australia, the Melbourne branch was supplied with dies for striking Australian silver florins, shillings, sixpences and threepences under contract with the Australian Federal government. Like the gold coins, these early Commonwealth issues bore the mint mark M to differentiate them from coins struck in London (which bore no mint mark).

Proof Coin - 1 Shilling, Specimen Strike, Australia, 1916, reverse, first silver coins struck at Melbourne (with mint mark M).
Source: Museum Victoria
From 1919, bronze pennies were also struck at the Melbourne Mint (halfpennies were produced in Sydney).

Specimen Coin - 1 Penny, Proof Strike, Australia, 1919, reverse, first bronze coins struck at Melbourne.
Source: Museum Victoria
In 1930 the mint experimented with producing its own master tools, used to make working dies. This experiment led to the production of Australia’s rarest circulating coin, the 1930 penny.

Proof Coin - 1 Penny, Australia, 1930, reverse.
Source: Museum Victoria
With the decision in the 1960s to adopt decimal currency in Australia, Melbourne Mint came to play an important role, together with the new Commonwealth Mint in Canberra and the Perth Mint in Western Australia. Once the need for massive numbers of new coins had passed the Canberra mint was able to cope with the annual needs of Australia’s economy. As there was no longer any need for the Commonwealth to offer contracts for coin production to branches of the Royal Mint, the Melbourne Mint was closed in 1972.