The fyrk was Sweden's smallest denomination in an era when the kingdom was hemorrhaging silver into military campaigns — Karl IX, still operating as regent-turned-protector rather than crowned king (he wouldn't formally take the throne until 1604), needed coinage that stretched metal as far as possible. Billon at .141 fineness does exactly that. The "Big crowns" variety distinction under SM#31a reflects die differences documented by Swedish numismatists, separating this type from the concurrent small-crown issues struck the same year at the same facilities.
The fyrk was Sweden's smallest denomination in an era when the kingdom was hemorrhaging silver into military campaigns — Karl IX, still operating as regent-turned-protector rather than crowned king (he wouldn't formally take the throne until 1604), needed coinage that stretched metal as far as possible. Billon at .141 fineness does exactly that. The "Big crowns" variety distinction under SM#31a reflects die differences documented by Swedish numismatists, separating this type from the concurrent small-crown issues struck the same year at the same facilities.