4 Reales - Felipe II

Potosí's earliest coinage was notoriously crude even by macuquina standards. The mint had opened in 1574 — no, the Casa de la Moneda at Potosí began striking coins in 1574 under a royal charter, but assay records confirm experimental or irregular production as early as the late 1560s, which is precisely the window this piece occupies. Output during these first years fell under intense Crown scrutiny after widespread reports of fineness fraud among local assayers, a scandal that would eventually culminate in prosecutions and executions in the 1640s.

The specific assayer responsible for this emission remains the key variable separating KM#10.1 from KM#10.2.