achate
noun
ach·ate
ˈa-kət
variants or achates
ə-ˈkā-tēz 
plural achates
ˈa-kəts,
ə-ˈkā-tēz
: agate sense 1
Word History
Etymology
Middle English achate, from Old French, from Latin achates
First Known Use
13th century, in the meaning defined above