The text is an analysis of two hoards of copper shillings (szeląg) of John Casimir Vasa (1648–1668) dating from the years 1659–1666, found in one of the arable fields at Rokitno (Lubartów County) in 1981 and 2011. The first one is made up entirely of 3,530 copper shillings (so called boratynka in singular), while in the other one, with 10,218 pieces, the same coin type accounts for 99.9%. The structures of these two hoards from Rokitno correspond with some other representative deposits of the same coin type from the localities such as Idźki-Wykno, Przasnysz, Terespol. This particular structure refers, among other things, to percentage shares of the Polish Crown and Lithuanian shillings as well as to how the individual mints and years of issue are represented in these types. The hoard unearthed in 1981 was deposited most probably in the early fourth quarter of the 17th century, whereas the one found in 2011 – shortly after 1695.

This article deals with the issue of King John Casimir’s copper shillings struck in 1659–1666, emerging from the analysis of the structure of large shilling hoards in relation to the contents of mint reports. It was conducted on the basis of representative, newly-described finds from Idźki-Wykno and Rokitno, as well as previously published deposits, encompassing more than 59,000 coins. On this basis, the global production volume of shillings was estimated along with the share of individual mints. These values prompt a response to the accusations of mintage abuse levelled against Tytus Livius Boratini. However, another premise emerged from the initial analysis of false shillings that helps to date hoards of copper shillings.