Agrellite

(repeating unit)NaCa2Si4O10FIMA symbolAre[1]Strunz classification9.DH.75Crystal systemTriclinicCrystal classPinacoidal (1)
(same H-M symbol)Space groupP1IdentificationColorWhite, grayish-white, greenish-whiteCrystal habitLath - shaped like a small, thin plaster lath, rectangular in shapeCleavageperfect [110]Mohs scale hardness5.5LusterpearlyStreakwhiteDiaphaneitytranslucentSpecific gravity2.88Optical propertiesbiaxialRefractive indexnα = 1.567 nβ = 1.579 nγ = 1.581Birefringenceδ = 0.014References[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.

See also

References

Wikimedia Commons has media related to Agrellite.
  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.


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