Tostão 'Λ-I'– João III 2nd type, Porto

João III's reign saw Portugal stretched impossibly thin — the empire ran from Brazil to Goa to the Spice Islands, and the crown's finances reflected it. The Porto mint operated intermittently under royal license during this period, its output distinguishable from Lisbon strikes by the 'Λ' mint mark. Second-type tostões were introduced to address subtle weight and fineness inconsistencies that had plagued the first emission.

Porto production across this fifteen-year window was never heavy. Survivors attributable to this specific type and mint with confidence are scarce in any grade.