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Agrellite

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Agrellite
Agrellite showing fluorescence in ultraviolet light
General
CategoryInosilicates
Formula
(repeating unit)		NaCa2Si4O10F
IMA symbolAre
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
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

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. Other localities include Murmansk Oblast, Russia, Dara-i-Pioz Glacier, Tajikistan, and Saima Complex, Liaoning, China. Common associates at the type locality include zircon, eudialyte, vlasovite, miserite, mosandrite-(Ce), and calcite.

Agrellite displays pink fluorescence strongly under shortwave and weakly under longwave ultraviolet light. The fluorescent activator is dominantly Mn, with minor Eu, Sm, and Dy.

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

See also

References

  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. ^ "Agrellite". www.mindat.org. Retrieved 2021-12-08.
  5. "Handbook of Mineralogy". www.handbookofmineralogy.org. Retrieved 2021-12-08.
  6. ^ "Luminescence, fluorescence and phosphorescence of minerals". www.fluomin.org. Retrieved 2021-12-08.


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