Tour Of Norway's Kongsberg Mint Museum

Recently, I visited the Kongsberg mining and mint museum in Norway. It had a very interesting exhibit of machinery used at the mint, as well as a great exhibit of coins and dies made at Kongsberg. Despite the low lighting, I was able to capture a few pictures of the exhibit. Most of the text comes from the museum.



From Christian IV to Harald V.
The first coins made from Kongsberg silver were struck in Copenhagen under king Christian IV. The king's mint was established in Norway in 1628. After a few years, minting at Akershus fortress was moved to Kongsberg in 1686.

The oldest Norwegian coin retained was struck in 995 A. D. during the reign of King Olav Tryggvason. In the following period till around 1570 sporadic coining took place in different parts of Norway (e.g. in Tonsberg, Hamar, Trondheim, Skien and Bergen). As a consequence of the discovery of important silver deposits in the Kongsberg area, Norwegian coin production was resumed in 1628 by the establishment of a mint in Christiania (Oslo). In 1686 a new mint was built at Kongsberg next to the smelter for the silver mines, on the very spot where the Royal Norwegian Mint is located today. The traditional mining symbol - the crossed hammer and chisel - has ever since been the hallmark of coins struck at Kongsberg. The mint in Christiania was closed down in 1695.

Smelting
The coin metal, appropriately alloyed, was smelted in charcoal burning smelting furnaces. From the crucible the molten alloy was poured into molds to form flat ingots. The introduction of rotating casting molds greatly increased the efficiency of this process. On the walls you will find different tools used for smelting and casting. The crucible dates from the last half of the 18th century.



Rotating casting molds:


Rolling
In the rolling mill the strips (flat ingots of coin metal) were rolled down to the appropriate thickness.



Blanking
From the rolling mill the strips went to the blanking machine, where the blanks of required diameter were cut out.



Rimming
In the rimming machine the blanks were bumped to raise a rim, which would facilitate the coinage process. The rim was a little higher than the relief. Rimming with decor was originally introduced as a precaution against reduction of the coin's value through filing or cutting.



Coining
From the 17th century the screw press was used for the striking of big coins. One person put the blank under the press plunger, while two to four persons moved the swivel arms back and forth. The movement was thus transferred to the die Up to 30 coins a minute are said to have been struck.



In 1837 The Royal Mint procured a new type of coining press, the so-called toggle joint press, invented by the German Uhlhorn in 1817 and named after him. From the 1860s the Uhlhorn press probably took over most of the coin production, while the screw press was used for the coining of medals. The press displayed in this room dates from 1874, and was in use until 1966.



The reduction lathe
This reduction lathe dates from the 1880s and is the first one to be used at the mint. This invention greatly facilitated the work of the engraver, who could now create a galvano in plaster (15 to 25cm in diameter). The reducing machine transferred the design to a matrix from which the die was produced.



Plaster model for 1 Kroner coin minted from 1925-51:


In addition to the mint machinery, there is a great exhibit on the die making process. The set below shows the progression from matrix (master hub) to working die: a. Matrix; b. master die; c. working hub; d. working die. On the right set, notice how there is a partial date on the matrix; the full date was added to the master die.



The museum also had some older dies; these date from Christian 7 (1766-1808)



There was also an excellent collection of coins spanning the history of the Kongsberg mint. A few of these appeared to be proofs.





Kongsberg was established as a mint due to its proximity to rich silver deposits. It is world-famous for its distinctive native silver specimens. Here is a specimen from the museum's silver exhibit. It weighs 25.25 lbs.