first time we see a reference to Oslo on a coin is from the time of Duke
Håkon Magnusson who issued a coin
with the inscription: MONETA ASLOIA. Håkon continued minting coins
in Oslo after he became king in 1299. On these pennies we can read the
inscription: MONETA OSLO(IE).
In the winter of 1531-1532, after fleeing to the Netherlands eight years earlier, Christian II attempted to re-conquer his hereditary throne with an army of mercenaries. The hired troops captured Oslo and besieged Akershus Fort. The siege dragged on and Christian started running out of funds. He was then offered the services of the mint-master and coining tools of his adversary, Mogens Gyldenstjerne, feudal lord of Akershus. In this way Christian II came to mint klippen.
Christian was given metal from the archbishop and other Norwegian bishops. At issue was the preservation of the Catholic faith and national policies, and a lot of church silver was now sent to the mint. This process was carried so far that the mint-master even tested the silver in the St. Halvard reliquary in Oslo. Whether or not we see this sacred relic in Christian's klippen is impossible to ascertain. However, these coins are made of unusually high-grade metal, with a silver content of more than 97%.
In 1628, a coin workshop was built in Christiania ? west of the old, fire-gutted Oslo ? for minting silver from Sandsvær. Goldsmith Anders Pedersen was appointed mint-master on 28 April the same year. The mint workshop in Christiania was shut down in 1695.