Lxxx Réis '4 Vintens' - João IV Porto

João IV's accession in 1640 ended sixty years of Iberian Union, and Portugal's mints scrambled to produce a distinctly Portuguese coinage almost immediately. The Porto mint's output of this denomination was critical to re-establishing a functioning domestic silver circulation after decades in which Spanish currency had dominated. Porto struck alongside Lisbon throughout this period, and pieces from the two mints are distinguished by mint mark rather than any meaningful typological difference.

The "4 Vintens" designation reflects the coin's valuation in the older vinténs accounting system — eighty réis equaling four vintens of twenty réis each — a dual nomenclature that persisted in popular use long after official documentation standardized on the réis figure.