Almandine

Almandine

Infobox mineral
name = Almandine
category =
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formula =
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color = reddish orange to red, slightly purplish red to reddish purple and usually dark in tone
habit =
system =
twinning =
cleavage = none
fracture = conchoidal
mohs = 7 - 7.5
luster = greasy to vitreous
polish = vitreous to subadamantine
refractive = 1.790 (+/- .030) Gemological Institute of America, "GIA Gem Reference Guide" 1995, ]
opticalprop = Single refractive, and often anomalous double refractive
birefringence = none
dispersion = .024
pleochroism = none
fluorescence= inert
absorption = usually at 504, 520, and 573nm, may also have faint lines at 423, 460, 610 and 680-690nm
streak =
gravity = 4.05 (+.25, -.12)
density =
melt =
fusibility =
diagnostic =
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Almandine, also known incorrectly as almandite, is a species of mineral belonging to the garnet Group. The name is a corruption of alabandicus, which is the name applied by Pliny the Elder to a stone found or worked at Alabanda, a town in Caria in Asia Minor. Almandine is an iron alumina garnet, of deep red color, inclining to purple. It is frequently cut with a convex face, or en cabochon, and is then known as carbuncle. Viewed through the spectroscope in a strong light, it generally shows three characteristic absorption bands. Almandine is one end-member of a mineral solid solution series, with the other end member being the garnet pyrope. The almandine crystal formula is: Fe3Al2(SiO4)3. Magnesium substitutes for the iron with increasingly pyrope-rich composition.

Almandine occurs rather abundantly in the gem-gravels of Sri Lanka, whence it has sometimes been called Ceylon-ruby. When the color inclines to a violet tint, the stone is often called Syrian garnet, a name said to be taken from Syriam, an ancient town of Pegu. Large deposits of fine almandine-garnets were found, some years ago, in the Northern Territory of Australia, and were at first taken for rubies and thus they were known in trade for some time afterwards as Australian rubies.

Almandine is widely distributed. Fine rhombic dodecahedra occur in the schistose rocks of the Zillertal, in Tyrol, and are sometimes cut and polished. An almandine in which the ferrous oxide is replaced partly by magnesia is found at Luisenfeld in German East Africa. In the United States there are many localities which yield almandine. Fine crystals of almandine embedded in mica-schist occur near Fort Wrangell in Alaska. The coarse varieties of almandine are often crushed for use as an abrasive agent.

References

*1911


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Look at other dictionaries:

  • Almandine — Al man*dine, n. [LL. almandina, alamandina, for L. alabandina a precious stone, named after Alabanda, a town in Caria, where it was first and chiefly found: cf. F. almandine.] (Min.) The common red variety of garnet. [1913 Webster] || …   The Collaborative International Dictionary of English

  • almandine — ALMANDINE. sub. fémin. Espèce de rubis …   Dictionnaire de l'Académie Française 1798

  • almandine — [al′məndīt΄al′mən dēn΄, al′məndin΄] n. [ML alamandina < LL Alabandina (gemma), stone from Alabanda, city in the interior of CARIA] a purplish red variety of garnet, Fe3Al2 (SiO4) 3, used as an inexpensive gem and an abrasive: sometimes called… …   English World dictionary

  • almandine — /al meuhn deen , duyn , din/, n. a mineral, red iron aluminum garnet. [1670 80; < F, MF < ML alamandina, alabandina a precious stone, prob. a kind of garnet, equiv. to Alaband(a) a town in Asia Minor + ina, fem. of inus INE1; cf. ME alabaundaryne …   Universalium

  • almandine — almandin [ almɑ̃dɛ̃ ] n. m. , almandine [ almɑ̃din ] n. f. • 1898, XVIIe; var. de alabandite ♦ Grenat aluminoferreux. ⇒ALMA(N)DIN, (ALMADIN, ALMANDIN) subst. masc., ALMA(N)DINE, (ALMADINE, ALMANDINE)subst. fém. MINÉR., JOAILL …   Encyclopédie Universelle

  • almandine — almandinas statusas T sritis chemija apibrėžtis Mineralas. formulė Fe₃Al₂[SiO₄]₃ atitikmenys: angl. almandine rus. альмандин …   Chemijos terminų aiškinamasis žodynas

  • almandine — noun Etymology: Middle English alemaundine, from Anglo French alamandine, alteration of Old French alabandine, from Medieval Latin alabandina, from Alabanda, ancient city in Asia Minor Date: 15th century almandite …   New Collegiate Dictionary

  • almandine — noun A deep red color, inclining to purple, mineral belonging to the garnet group with chemical formula FeAl(SiO) …   Wiktionary

  • almandine — n. red colored mineral, almandite …   English contemporary dictionary

  • almandine — [ alməndi:n, dʌɪn] noun a kind of garnet with a violet tint. Origin ME: from obs. Fr., alt. of alabandine, from med. L. alabandina (gemma), jewel from Alabanda , an ancient city in Asia Minor where these stones were cut …   English new terms dictionary

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