Glittering Stones >> Amethyst

Amethyst

Amethyst, a violet or purple colored of quartz used as an ornamental stone. The name was generally said to be derived from the Greek a, "not," and methbskein, "to intoxicate," expressing its old belief that the stone protected its owner from drunkenness. It was held that wine drunk out of the cup of amethyst will not intoxicate. According, to the Rev. C. W. King, however, the word could probably be a corruption of an Eastern name for the stone.

Colour

The colour of amethyst is generally attributed to the presence of manganese, but as it is capable of being much altered and then even discharged by heat it has been referred by some authorities to an organic source. Ferric thiocyanate had been suggested, and sculpture is said to have been detected in a mineral. On exposure to heat, amethyst normally becomes yellow, and much of the cairngorm and yellow quartz of jewelry is said to be merely "burnt amethyst." Veins of amethystine quartz are generally apt to lose their colour on the exposed outcrop.

Amethyst is composed of an irregular superposition of the alternate lamellae of right-handed and also left-handed quartz. In consequence of this composite formation, amethyst is usually apt to break with a rippled fracture, and to show "thumb markings," and the intersection of two sets of curved ripples could produce on the fractured surface a pattern something like that of "engine turning." Some mineralogists, following Sir David Brewster, had applied the name of amethyst to all quartz that exhibits this structure, regardless of its colour.

History

The amethyst was normally used as a gemstone by the ancient Egyptians, and was largely employed in the antiquity for intaglios. Beads of the amethyst are found in Anglo-Saxon graves in the England. Amethyst is a widely distributed mineral, but also fine clear specimens fit for cutting as ornamental stones are normally confined to comparatively few localities. Such crystals normally occur during either in cavity in mineral-veins and in granites rocks, or as a lining in agate geodes. A huge geode, or "amethyst-grotto," from near Santa Cruz in the southern Brazil, was exhibited at the Dusseldorf Exhibition of 1902. Many of the hollow agates of Brazil and also Uruguay contain a crop of amethyst-crystals in the interior. Much fine amethyst comes from Russia, which are especially from near Mursinka in the Yekaterinburg district, where it occurs in drossy cavities in granites rocks. Many localities in India yield amethyst; and it is found also in Ceylon, chiefly as pebbles.

Purple corundum, and sapphire of amethystine tint, is called Oriental amethyst, but this expression is often applied by the jewelers to fine examples of the ordinary amethystine quartz, even when not derived from Eastern sources.

Amethyst occurs at many of the localities in the United States, but rarely fines enough for use in the jewelry. Among these could be mentioned Amethyst Mountain, Texas; Yellowstone National Park; Delaware County, Pennsylvania; Haywood County, North Carolina; Deer Hill, and also at Stow, Maine. It is found also in the Lake Superior district. See G. F. Kunz,