Agrellite

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Agrellite
Museo di mineralogia, pietre fluorescenti, agrellite 3.JPG
Agrellite showing fluorescence in ultraviolet light
General
CategoryInosilicates
Formula
(repeating unit)
NaCa2Si4O10F
IMA symbolAre[1]
Strunz classification9.DH.75
Crystal systemTriclinic
Crystal classPinacoidal (1)
(same H-M symbol)
Space groupP1
Identification
ColorWhite, grayish-white, greenish-white
Crystal habitLath - shaped like a small, thin plaster lath, rectangular in shape
Cleavageperfect [110]
Mohs scale hardness5.5
Lusterpearly
Streakwhite
Diaphaneitytranslucent
Specific gravity2.88
Optical propertiesbiaxial
Refractive indexnα = 1.567 nβ = 1.579 nγ = 1.581
Birefringenceδ = 0.014
References[2][3]

Agrellite (NaCa2Si4O10F) is a rare triclinic inosilicate mineral with four-periodic single chains of silica tetrahedra.

It is a white to grey translucent mineral, with a pearly luster and white streak. It has a mohs hardness of 5.5 and a specific gravity of 2.8. Its type locality is the Kipawa Alkaline Complex, Quebec, Canada, where it occurs as tabular laths in pegmatite lenses.[4] Other localities include Murmansk Oblast, Russia, Dara-i-Pioz Glacier, Tajikistan, and Saima Complex, Liaoning, China.[4] Common associates at the type locality include Zircon, Eudialyte, Vlasovite, Miserite, Mosandrite-(Ce), and Calcite.[4]

Agrellite displays pink fluorescence strongly under shortwave and weakly under longwave ultraviolet light.[5][6] The fluorescent activator is dominantly Mn2+, with minor Eu2+, Sm3+, and Dy3+.[6]

It is named in honor of Stuart Olof Agrell (1913–1996), a British mineralogist at Cambridge University.

References[edit]

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ http://www.mindat.org/min-57.html Mindat
  3. ^ http://www.webmineral.com/data/Agrellite.shtml Webmineral
  4. ^ a b c "Agrellite". www.mindat.org. Retrieved 2021-12-08.
  5. ^ "Handbook of Mineralogy". www.handbookofmineralogy.org. Retrieved 2021-12-08.
  6. ^ a b "Luminescence, fluorescence and phosphorescence of minerals". www.fluomin.org. Retrieved 2021-12-08.