Agrellite

Agrellite (NaCa2Si4O10F) is a rare triclinic inosilicate mineral with four-periodic single chains of silica tetrahedra. The IMA symbol is Are.[3]

Agrellite
Museo di mineralogia, pietre fluorescenti, agrellite 3.JPG
Agrellite showing fluorescence in ultraviolet light
General
CategoryInosilicates
Formula
(repeating unit)
NaCa2Si4O10F
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[1][2]

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, QuebecCanada, 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.

This article uses material from the Wikipedia article
 Metasyntactic variable, which is released under the 
Creative Commons
Attribution-ShareAlike 3.0 Unported License

Note

This article uses material from the Wikipedia article
 Metasyntactic variable, which is released under the 
Creative Commons
Attribution-ShareAlike 3.0 Unported License
.