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AMETHYST
, a See also:violet or See also:purple variety of See also:quartz used as an ornamental See also: J . W . See also:Judd that this structure may be due to See also:mechanical stresses . In consequence of this composite formation, amethyst is apt to break with a rippled fracture, or to show " thumb markings," and the intersection of two sets of curved ripples may produce on the fractured See also:surface a See also:pattern something like that of " See also:engine turning." Some mineralogists, following See also:Sir D . See also:Brewster, apply the name of amethyst to all quartz which exhibits this structure, regardless of its colour . The amethyst was used as a See also:gem-stone by the See also:ancient Egyptians, and was largely employed in antiquity for intaglios . Beads of amethyst are found in Anglo-Saxon See also:graves in See also:England . Amethyst is a very widely distributed mineral, but See also:fine clear specimens See also:fit for cutting as ornamental stones are confined to comparatively few localities . Such crystals occur either in cavities in mineral-veins and in granitic rocks, or as a lining in See also:agate geodes . A huge geode, or " amethyst-grotto," from near See also:Santa Cruz in See also:southern See also:Brazil, was exhibited at the See also:Dusseldorf See also:Exhibition of 1902 . Many of the hollow agates of Brazil and See also:Uruguay contain a See also:crop of amethyst-crystals in the interior . Much fine amethyst comes from See also:Russia, especially from neat Mursinka in the See also:Ekaterinburg See also:district, where it occurs in drusy cavities in granitic rocks .
Many localities in See also:India yield amethyst; and it is found also in See also:Ceylon, chiefly as pebbles
.
Purple See also:corundum, or See also:sapphire of amethystine tint, is called See also:Oriental amethyst, but this expression is often applied by jewellers to fine examples of the See also:ordinary amethystine quartz, even when not derived from Eastern See also:sources
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Amethyst occurs at many localities in the See also:United States, but rarely fine enough for use in jewellery
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Among these may be mentioned Amethyst See also:Mountain, See also:Texas; Yellowstone See also:National See also:Park; See also:Delaware Co., See also:Pennsylvania; See also:Haywood Co., See also:North Carolina; See also:Deer See also: |
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