German South West African Mark the gold content of the British Pound Sterling was 7.3224 grams, while the gold content of 20 marks was 7.168 grams. According to Gresham's Law, "bad money drives out good", so the "bad" Mark replaced the "good" British Pound Sterling. In 1901, the German Mark became the official currency of German South West Africa, hence replacing the 20 and 5 mark denominations of the German South West African Mark, for which they were also demonetized (although, they continued use in the metropolis of German South West Africa until 1907). In 1923, the coins of the German South West African Mark
Gresham's law been noted much earlier, in the 14th century, by Nicole Oresme. In the year that Gresham was born, 1519, it was described by Nicolaus Copernicus in a treatise called "Monetae cudendae ratio": "bad (debased) coinage drives good (un-debased) coinage out of circulation." Copernicus was aware of the practice of exchanging bad coins for good ones and melting down the latter or sending them abroad, and he seems to have drawn up some notes on this subject while he was at Olsztyn in 1519. He made them the basis of a report which he presented to the Prussian Diet held in