The Spanish 8 reales is arguably the most important coin in world history — the “piece of eight” that became the model for the US dollar and circulated as legal tender in the United States until 1857. Struck at Mexico City, Potosí, Lima, and other colonial mints, the pillar (columnario) type with the Pillars of Hercules is the most iconic. This entry covers the types, mints, and what collectors verify.
Key facts
- The 8 reales (“Spanish dollar,” peso, duro, piece of eight) was struck from the 1500s through the 1800s in Spanish and colonial mints; New World mints are distinguished by the Pillars of Hercules reverse design.
- Pillar dollars (“columnarios”) were minted 1732–1773 with the crowned globes between the Pillars of Hercules, PLUS ULTRA motto, and VTRAQUE VNUM legend; the later portrait type (from 1772) is a different type, not a pillar dollar.
- Main colonial mints: Mexico City, Potosí, Lima (minor: Bogotá, Popayán, Guatemala City, Santiago); the mint mark on the reverse identifies origin.
- Specifications (examples): Mexico City 1771, 27.07g, 39mm, silver; the 1728 standard was 0.9167 fine.
- Pillar dollars were legal tender in the United States until 1857 — the direct ancestor of the US silver dollar.
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