29 amethyst absorption spectrum – amherst stone amethyst absorption spectrum; absorption spec- amethyst inclusions; ® inclusion in amethyst . trums of amethyst is not distinctive but two in the amethystine; a variety of quartz or glass with patchy yellow-green seen at 520 and 550 nm. amethyst coloring. nm 700 650 600 550 500 450 400 amethystine chalcedony; light violet to gray-purple variety of amethyst-chalcedony from Arizona, orange yellow green violet red blue USA, which is commercially known as damsonite . ® Chalcedony . amethystine quartz; massive quartz with patchy 550 520 amethyst coloring. ® Amethyst quartz . Absorption spectrum of amethyst amethystine sapphire; same as violet to purplish amethyst basaltin; a German misleading term for sapphire . pale amethyst colored apatite. amethystizonats; the fiery red hue passes at the edges amethyst basaltine; a misleading term for pale ame- into amethyst violet color. thyst colored apatite. amethyst, -name of; the term is derived from the amethyst basanite; a pale yellow reddish beryl. Greek name amethystos meaning not drunken refer amethyst basanite; a color designation meaning vio- to a supposed power to mitigate alcoholic excess. In let or purplish. Farsi (Persian) gemast (not drunken). amethyst–citrine; a rock crystal containing both min- amethyst lithia; a misnomer for lilac spodumene. erals with both colors. Also called ametrine o r trystine . amethyst oriental; a misnomer for violet corundum. Heat treatment of amethyst can produce similar stone. amethyst point; hexagonal amethyst crystal from an amethyst, -color interference of; frequently color amygdaloidal geode. interference bands caused due to twinning can be amethyst quartz; a variety of banded amethyst, in which milky quartz or agate is included. amethyst quartz; a commercial term to designate badly fashioned cabochon from amethyst quartz, Colored interference especially those from amethystine quartz. bands seen in natural quartz or amethyst, synthetic; ® synthetic amethyst . amethyst due to Amethystus; sixth stone in Jewish High Priest twinning through in the direction of Breastplate. ® Breastplate . optic axis by amethyst, -zebra stripes in; a typical liquid-filled crossed Nicols duct inclusion in parallel arrangement with a struc- ture appears as striations similar to zebra or tiger seen in natural quartz or amethyst by using thin sec- tion and crossed Nicols under microscope. amethyst, -color of; a pale violet to purple or violet, transparent variety of quartz. The color being due to 2+ 3+ present of Fe or Fe and traces of manganese, owing Zebra or to irregular color zoning. When amethysts are heated tiger to 350–400°C under reducing conditions or irradiated, stripes in amethyst the color changes to light to dark yellow, which is fre- quently misnomered as citrine . Amethyst containing Fe 3+ before irradiation changes to yellow, when con- taining Fe 2+ the color turns green, which is called pra- siolite or greened amethyst . When the stone is heated to 350–400°C obtains a parti-color of amethyst–citrine stripes, which may occur due to some kind of growth known as ametrine . disturbance or pressure causing internal shearing. amethyst cut; cut as faceted gemstones in various ametrine; a combined term used for violet and yellow sizes, cabochon, or are tumbled. striped amethyst–citrine, which grows together, found amethyst imitation; a violet barium-glass. SG: 2.80. only in Anahi Mine, Bolivian. Used as a gemstone. RI: 1.542. amherst stone; ® blue stone . amianthus – ampelite 30 amianthus; ancient name for long, fine silky fibered polished surface shows closely patches with play- variety of asbestos such as chrysotile. of-color similar to that of black opal. Worn as amiantoid; an olive-green, coarse fibrous variety of brooch or pendant. Found in Alberta, Canada. asbestos. Sometimes it is impregnated in plastic to prevent Amici glass-prism; a lens system that is integral in damage and marketed as korite . ® Korite , fire some direct-vision spectroscopes consisting of marble , lumachelle two or three or more layers of glass of differing blue white beam yellow red section beside front Amici glass-prism Three ammonite forms from Trias, Cretaceous and Jurassic flint lens crown crown ammonite; an explosive substance, which contains 70–95% ammonium nitrate. An Amici compound prism in a spectroscope amorphism; the state or quality of being amorphous, such as absence of crystalline structure. refractive indices to give zero deviation at yellow amorphous; a term applied to minerals or gem wavelengths. The lens in the middle of the system materials, which have no definite internal arrange- is from lead glass (flint) and both of the ends are ment of the atoms or molecules, and hence no potassium-glass (crown glass). This lens system is external crystal form. Sometimes its properties arranged to give dispersion without deviation of are the same in all directions such as amber and the yellow color. glass. The term excludes the existence of any amicroscopic structure flaw; deviation from an ideal degree of order. Noncrystalline. ® Crystalline . crystal lattice in unit of 10 –7 to 4 × 10 –7 cm. amorphous; a term formerly used to describe rock AMICUT; ® Diaminir , Ltd . occurring in a continuous mass, which is not − divided into parts. amino group; the radical (NH2 ) in organic chemistry. amorphous mineral; a mineral with no definite aminobenzene; same as aniline . crystalline structure. aminoplastics resin; the name applied to the urea amorphous zircon; zircon, which has suffered a and thiourea or melamine in formaldehyde conden- break-down from crystalline form to an amor- sation products. They are synthetic resins of the phous zircon. Common in minerals containing bakelite type. Dyed and used as gemstone imitation. radioactive elements. The name applied to the low RI: 1.55–1.62. SG: 1.50. H: 2. Transparent to zircon, which has decomposed into nearly amor- translucent. phous SiO2 and ZrO2 from the normally full crys- Amiti Diamond; a stolen diamond of 31 cts, was talline zircon mineral. Also called metamicts . owned by Mrs. N. Coffin, her girl’s name was Amiti; amosite; an iron rich anthophylite a variety of from Bedford, Massachusetts, USA. asbestos in yellow color from Transvaal, South ammolite; a term used for doublet made from Africa. lumachelle, a fossiliferous fire marble usually amourant; a commercial term for doublet or com- ammonites or baculites. ® Ammonite . posite stone made of synthetic white sapphire top ammonalaun; a colorless to gray mineral of alum and strontium titanate on the bottom. ampangabeite; same as samarskite . group with chemical formula: NH4 Al(SO4 )2 . 12H2 O. H: 1.5. SG: 1.650. RI: 1.459. Also called ampelite; an old and obsolete term for shale contain- tschermigite . ing bituminous carbonaceous. ammonite; an iridescent gem material derived from ampelite; another term for cannel coal , carbonaceous aragonite-nacreous layer of ammolite fossils. The schist . 31 amphibole – amygdale amphibole; the name applied to a dark colored ampullar pearl; natural pearl formed in the ampulla group of ferromagnesium silicate minerals whose or epidermis of the oyster, which is distinguished from cyst pearl and muscle pearl. c Amsterdam; very important diamond-cutting center b in the Netherlands. a Amsterdam Black Diamond; a pear-shaped dia- Њ 124 b mond of 33.74 cts, cut from an opaque, rough a stone weighing 55.85 cts. It was exhibited at the cleavage degrees 700th anniversary celebration of the city of Amsterdam in 1975. Also called Amsterdam Diamond . cleavage pattern Amsterdam brilliant cut; ® Amsterdam cut . cleavage in concern with strucrue amphibole structure Amsterdam cut; a brilliant cut same as European cut . Synonym: Amsterdam brilliant cut. Amphibole structure and cleavage Amsterdam Diamond; same as Amsterdam Black physical and chemical characters serve to link them Diamond . together in one family of inosilicates with double Amsterdam rose; same as Holland rose . chains and chemical formula of A2 B5 (Si,Al)8 O22 (OH)2 . amulet; charm objects used as faithfulness and Where A = Mg, Fe 2+ , Ca, or Na, and B = Mg, Fe 2+ , divine emblems, which is only a step away from Fe 3+ or Al. They are silicates of magnesium, iron, being transformed into talismans, ensuring divine calcium, sodium, and sometimes potassium. The protection for its wearer, to prevent disease or mis- minerals are characterized by prismatic columnar fortune, and to ward off evil, which simply is a or fibrous crystals. Hornblende, asbestos, and cabalistic sign. For example, scarab or dung beetle nephrite are essential amphibole minerals. often carved from green stone was one of the per- Crocidolite is a blue member of asbestos amphi- sonifications of the sun and a symbol of eternity in bole mineral, which changed by oxidation to a fine golden-brown, is known as tiger’s-eye or tiger-eye . Occasionally has been silicified (pseudomorph) without alteration of the blue color, it is known as sapphire-quartz , azure-quartz , siderite , or hawk’s- eye , or falcon’s-eye . amphibole; a mineral of the amphibole group such as hornblende, actinolite, anthophyllite, cumming- tonite, arfvedsonite, riebeckite, tremolite, glauco- phane. Also called amphibole group . fusiform bead amphibole group; same as amphibole . Some modern amulets cut or rough from crystals amphibolid; ® amphibolite . ancient Egypt. In Roman times and more popular amphibolite; a crystalline, coarse-grained rock, con- in Middle Ages, people wore a gemstone engraved sisting of amphiboles,