10 Réis - João VI Big armillary sphere - Goa mint

João VI authorized continued copper coinage at the Goa mint despite the broader disruption caused by his court's relocation to Brazil in 1807 — a flight from Napoleonic invasion that left Portuguese colonial administration operating at a considerable remove from Lisbon for over a decade. The Goa mint, one of the oldest continually operating European-established mints in Asia, maintained production largely on its own institutional momentum during this period.

The "big armillary sphere" designation distinguishes this from a concurrent smaller-type striking, a practical die classification that emerged because both types circulated simultaneously in the Estado da India.