The discovery of gold in the colony New South Wales in 1851 prompted a surge of immigration among prospector seeking wealth in the new colony. While the lands were resource rich, the colony lacked the facilities to monetise the gold and the process in sending the gold to London for monetisation was slow and expensive. To help resolve this, the Royal mint sought to open a branch in Sydney so that the gold would not need to be shipped to London to be coined. The Sydney mint opened in 1855 in the rear of the Rum Hospital, situated on Macquarie Street in the Sydney CBD(Sydney Mint Museum, 2017).
The Type II, or wreathed bust Sydney Mint Half Sovereign was struck from 1857 though some examples are known to be dated 1855 - these were likely struck in 1857. Rather than using copper to harden the metal as the Royal Mint did, the Sydney Mint used silver(Melbourne Museum Discovery Centre, 2008). The reverse design featured a banksia wreath tied into a bow, below and surrounding the word AUSTRALIA; these are positioned below a crown with the legend SYDNEY MINT and HALF SOVEREIGN encircling the entire design. This was the only time a colony would ever deviate from the imperial design though it was short-lived with the Sydney Mint reverting to the imperial shield design in 1871.
Excluding varieties and overdates the key date of the series is undoubtedly the 1855 if this is to be considered a business strikewhich is known by just 3 examples. Aside from this the 1860 is also scarce with about 200 to 250 examples known.
Mintage figures for the series are unreliable with the Royal mint Sydney reporting figures clearly inconsistent with survival rates with some years reporting no coins being struck when they're certainly known to exist. The Sydney mint also took a lot of initiative in methods of prolonging the working lives of diessuch as re-punching lettering resulting in a number of misspelling errors, overdating and re-using dies from previous years.
The Sydney mint series is marked by low survival rates, likely due to the gold-silver alloy giving them a higher intrinsic value than their face value making it profitable to melt them down for their metal content. This gold-silver alloy continued for the entire series despite official protests to the Colonial Treasurer by Sydney based chemist Charles Watt with the Mint Master arguing that the extra value from the silver content was a decided advantage(Watt, C., Ward E. W. and Lane, H., 1863).