The publication of a new numismatic source, a variety of the quarter kopeck (polushka), which was coined by the Kolyvan mint in 1783 again describes this unusual object and draws the scientific attention to the question about the reasons and circumstances of its appearance. This coin represents a new sample of the coin which was minted at the Nizhniy Suzun mint in the beginning of the 1780s. It contains some elements of the previous type of the coin, named Siberian polushka. These elements are the weight of the coin and the details of the Siberian Polushka indicating the four letters of the denomination legend. The only possible explanation of the given phenomenon is the use for its stamping of the coin billets of the Siberian polushka, which had smaller weight than the new polushka of the imperial type, and also the use of altered stamps of the Siberian polushka. The analysis of the circumstances of the copper coin production process in Altai at the end of the 70s — the first half of the 80s of the 18 century allows concluding that such a defective coin could emerge under circumstances of insufficient coordination in the activity of various administrative structures of the imperial and local levels, and owing to the technical backwardness of the household complex of medieval Russian Emperor’s Cabinet.