10 Kopeks. Siberian coppers were made out of copper by-product of a silver mine in the Altai. Since the copper contained some silver and even gold it was made to a lower weight standard. The KM stands for Kolvyan Copper (Med'), and is not a mint mark. Series ran from 1764-1781 after which the Kolyvan mint started producing regular-style coppers with the KM mintmark