In the 8th century Charlemagne declared that 240 pfennigs should be minted from a pound (c. 408 grams) of silver. A single coin had a mass of 1.7 grams after the coinage reform of circa 790. Until the 13th century, the pfennig was made from real silver, and thus of high value. From the 12th century on, the German King was no longer able to enforce the regalia to mint coins, so many towns and local lords made their own coins. Mostly, less valuable metals (usually copper with trace additions of tin and lead) and less metal per coin was used, so different pfennigs had different values. Within a few decades, two parallel denominations had developed: high-value ' ("white pennies") with over 50 percent of silver and low-value ' ("black pennies") with a very high content of copper and little silver or no silver at all.