Verses with the word agate in the Old Testament (3 verses):

Exodus 28:19
And the third row a ligure, an agate, and an amethyst.

Exodus 39:12
And the third row, a ligure, an agate, and an amethyst.

Ezekiel 27:16
Syria was thy merchant by reason of the multitude of the wares of thy making: they occupied in thy fairs with emeralds, purple, and broidered work, and fine linen, and coral, and agate.