1/2 Tostão 'o-o' - João III 2nd type, Porto

João III ruled Portugal during the peak of the Carreira da Índia, when silver from Atlantic trade and gold from West Africa strained the royal mint system to capacity. Porto's house — the Casa da Moeda do Porto — struck this second type alongside Lisbon during a narrow two-year window, identifiable by the characteristic 'o-o' mint mark punctuation that distinguishes it from capital production. The Porto mint operated intermittently throughout the sixteenth century, pressed into service when Lisbon's output could not meet demand.

Gomes catalogues this as J3 89, placing it among the later emissions of João's reign — he died in June 1557, which closes the striking window hard.