Onyx
A precious stone whose properties were believed to resemble
those of jasper; it was also supposed to increase saliva in
boys and cause bad dreams. If applied to the eye, it was believed
to remove anything noxious.
The onyx was also believed to create strife, cause melancholy,
and cure epilepsy. According to the Bible, an onyx was
the eleventh stone in the breastplate of the High Priest (Exod.
2820), but it is possible that this stone (in Hebrew, shoham) is
known today as beryl.