rational, where it likely represented the tribe of Asher. The etymological derivation of the Hebrew word is unclear, but the stone has generally been acknowledged to be the agate. The Hebraic derivation derives shbw from shbb "to flame"; it may also be related to Saba (shba). Caravans having brought the stone to Palestine. The Greek and Latin names are taken from the river Achates (the modern Dirillo), in Sicily, where this stone was first found (Theophrastus, "De lapid.", 38; Pliny, "Hist. nat.", XXXVII, liv). The stone belongs to the silex family (chalcedony species) and is formed by deposits of siliceous beds in hollows of rocks. This mode of formation results in the bands of various colours which it contains. Its conchoidal cleavage makes it susceptible to a highly polished state. Various medicinal powers were attributed to this stone until far into the Middle Ages. Agate was supposed to void the toxicity of all poisons and counteract the infection of contagious diseases; if held in the hand or in the mouth, it was believed to alleviate fever. Within mythology, the eagle placed an agate in its nest to guard its young against the bite of venomous animals, and the red agate was credited with the power of sharpening vision. At present, agate and onyx differ only in the manner in which the stone is cut: if it is cut to show the layers of colour, it is called agate; if cut parallel to the lines, onyx. Formerly, an agate that was banded with well-defined colours was the onyx. The banded agate is used for the manufacturing of cameos. Amethyst Amethyst, Heb. ahlmh; Sept. amethystos, also Apoc., xxi, 20. This is the twelfth and last stone of the foundation of the New Jerusalem. It is the third stone in the third row of the rational, representing the tribe of Issachar (Ex., xxviii, 19; xxxix, 12); the Septuagint enumerates it among the riches of the King of Tyre (Ezech., xxviii, 13). The Greek name alludes to the popular belief that amethyst prevented intoxication; as such, drinking vessels were made of amethyst for festivities, and carousers wore amulets made of it to counteract the action of wine. Abenesra and Kimchi explain the Hebrew ahlmh in an analogous manner, deriving it from hlm, to dream; hlm in its first meaning signifies "to be hard". A consensus exists regarding the accuracy of the translation among the