 Silver 20 kopeks were introduced in 1820, followed by copper 10 kopeks minted between 1830 and 1839, and copper 3 kopeks introduced in 1840.Between 1828 and 1845, platinum 3, 6 and 12 rubles were issued.In 1860, silver 15 kopeks were introduced, due to the use of this denomination (equal to 1 złoty) in Poland, whilst, in 1869, gold 3 rubles were introduced.