Amblygonite
Amblygonite
General
Category Phosphate minerals
Chemical formula (Li,Na)AlPO4(F,OH)
Strunz classification 08.BB.05
Identification
Color Generally white or creamy, but can also be colorless or pale yellow, green, blue, beige, gray, brown or pink.
Crystal habit Prismatic to columnar form
Crystal system Triclinic
Twinning Microscopic polysynthetic twinning common
Cleavage [100] Perfect, [110] Good, [011] Distinct
Fracture Irregular/Uneven,Sub-Conchoidal
Mohs scale hardness 5.5 - 6[1]
Luster Vitreous to pearly[1]
Specific gravity 2.98 - 3.11
Polish luster greasy to vitreous (in gem material)[1]
Optical properties Double refractive, biaxial, may be either positive or negative[1]
Refractive index na=1.577 - 1.591,
nb=1.592 - 1.605,
nc=1.596 - 1.613
Birefringence .020 - .027[1]
Pleochroism weak to none[1]
Ultraviolet fluorescence very weak green in long wave, light blue phosphorescence in long wave and short wave [1]

Amblygonite is a fluorophosphate mineral, (Li,Na)AlPO4(F,OH), composed of lithium, sodium, aluminium, phosphate, fluoride and hydroxide. The mineral occurs in pegmatite deposits and is easily mistaken for albite and other feldspars. Its density, cleavage and flame test for lithium are diagnostic. Amblygonite forms a series with montebrasite, the low fluorine endmember. Geologic occurrence is in granite pegmatites, high-temperature tin veins, and greisens. Amblygonite occurs with spodumene, apatite, lepidolite, tourmaline, and other lithium-bearing minerals in pegmatite veins. It contains about 10% lithium, and has been utilized as a source of lithium. The chief commercial sources have historically been the deposits of California and France.

Contents

History

The mineral was first discovered in Saxony by August Breithaupt in 1817, and named by him from the Greek amblus, blunt, and gouia, angle, because of the obtuse angle between the cleavages. Later it was found at Montebras, Creuse, France, and at Hebron in Maine; and because of slight differences in optical character and chemical composition the names montebrasite and hebronite have been applied to the mineral from these localities. It has been discovered in considerable quantity at Pala in San Diego county, California; Caceres, Spain; and the Black Hills of South Dakota. The largest documented single crystal of amblygonite measured 7.62x2.44x1.83 m3 and weighed ~102 tons.[2]

Gemology

Transparent amblygonite has been faceted and used as a gemstone. As a gemstone set into jewelry it is vulnerable to breakage and abrasion from general wear, as its hardness and toughness are poor.[1] The main sources for gem material are Brazil and the U.S.. Australia, France, Germany, Namibia, Norway, and Spain have also produced gem quality amblygonite.[1]

Amblygonite from Taquaral, Itinga, Minas Gerais, Brazil. Scale at bottom is one inch, with a rule at one cm.


References

  1. ^ a b c d e f g h i (Gia), Gemological. Gem Reference Guide. City: Gemological Institute of America (GIA), 1988. ISBN 0-87311-019-6
  2. ^ P. C. Rickwood (1981). "The largest crystals". American Mineralogist 66: 885–907. http://www.minsocam.org/ammin/AM66/AM66_885.pdf. 

See also


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Look at other dictionaries:

  • Amblygonite — Amblygonite[1] Catégorie VIII : phosphates, arséniates, vanadates[2] …   Wikipédia en Français

  • amblygonite — ● amblygonite nom féminin Fluophosphate d aluminium et de lithium, de symétrie triclinique …   Encyclopédie Universelle

  • amblygonite — [am blig′ə nīt΄] n. [Ger amblygonit < Gr amblygōnios, obtuse angled < amblys, dull + gōnia, an angle (see KNEE) + it, ITE1] a usually greenish or whitish crystalline mineral, (Li,Na)Al(PO4)(F,OH): it is an ore of lithium and is found in… …   English World dictionary

  • amblygonite — /am blig euh nuyt /, n. a mineral, a lithium aluminum fluorophosphate, Li(AlF)PO4: an ore of lithium. [1840 50; < Gk amblygón(ios) (amblý(s) blunt, obtuse + goní(a) angle + os adj. suffix) + ITE1] * * * ▪ mineral       phosphate mineral composed… …   Universalium

  • amblygonite — ambligonitas statusas T sritis chemija apibrėžtis Mineralas. formulė (Li,Na)Al[(F,OH)|PO₄] atitikmenys: angl. amblygonite rus. амблигонит …   Chemijos terminų aiškinamasis žodynas

  • amblygonite — noun A mineral, a mixed fluoride and aluminophosphate of sodium and lithium that is an important ore of lithium …   Wiktionary

  • amblygonite — am·blyg·o·nite …   English syllables

  • amblygonite — am•blyg•o•nite [[t]æmˈblɪg əˌnaɪt[/t]] n. mir a mineral, a lithium aluminum fluorophosphate, Li(AlF)PO4, an ore of lithium • Etymology: 1840–50; < Gk amblygṓn(ios) obtuse angled …   From formal English to slang

  • amblygonite — /æmˈblɪgənaɪt/ (say am bliguhnuyt) noun a rare mineral, lithium aluminium fluorophosphate, Li(AlF)PO4, an ore of lithium found in pegmatites. {German Amblygonit, from Greek amblygōnios obtuse angled + it ite1} …   Australian English dictionary

  • amblygonite — noun a white or grey mineral consisting of lithium aluminum phosphate; a source of lithium • Hypernyms: ↑mineral • Substance Meronyms: ↑lithium, ↑Li, ↑atomic number 3 …   Useful english dictionary

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