agate

The word 'agate' entered English in the 16th century from French 'agathe', which itself came from Latin 'achates'. The Latin term was borrowed from the Greek 'akhátēs', the name of a river in Sicily where the stone was historically found. The ultimate origin is likely pre-Greek, reflecting the ancient and geographically specific source of this distinctive mineral. The word's journey from a proper noun for a river to a common noun for a type of chalcedony illustrates how material names often derive from their places of origin.

This is a simplex word. It is a loanword whose form does not readily break down into meaningful sub-parts in modern English.