So called, says Pliny (xxxvii. 10), from Achaʹtēs or Gagaʹtes, a river in Sicily, near which it is found in abundance.
“These, these are they, if we consider well,
That saphirs and the diamonds doe excell,
The pearle, the emerauld, and the turkesse bleu,
The sanguine corrall, amber’s golden hiew,
The christall, jacinth, achate, ruby red.”
Taylor: The Waterspout (1630).
Agate is supposed to render a person invisible, and to turn the sword of foes against themselves.