A stone varying in color, but of great hardness, being a variety of the flint. The agate, in Hebrew …, SheBO, was the center stone of the third row in the breastplate of the High Priest.

Agates often contain representations of leaves, mosses, etc., depicted by the hand of nature. Some of the representations on these are exceedingly singular. Thus, on one side of one in the possession of Velschius was a half moon, and on the other a star.

Kircher mentions one which had a representation of an armed heroine; another, in the church of Saint Mark in Venice, which had a representation of a king's head, adorned with a diadem; and a third which contained the letters I. N. R. I. (see Oliver's Historical Landmarks ii, page 522). In the collections of antiquaries are also to be found many gems of agate on which mystical inscriptions have been engraved, the significations of which are for the most part no longer understood.