Old and new testament alike. I could not believe its prevalence. I pick these examples randomly, with no preference to order other than the fact that I picks 'em as I finds 'em. In the magical works of the Magus, those who are learned in the arts of magic, sorcery, and astrology, Wednesday is allocated as a day to be devoted to Science, and on this day, in order to ply one's trade with accuracy and aplomb, one needs to wear a green robe, a necklace of hollow beads filled with mercury, and a ring with an agate set in it. The Bghai tribes of Burma had little stone statuettes, some presumably made of agate, to which blood offerings were made.
Man forgets to feed agate, agate eats man.
Of course they were also made of gold and silver and so on. Well of course there is. Nay nay good neighbors. Tyler-Adam Corp. Now then, many magical and not so magical designs were engraved on agate. To me, the answer is quite clear.