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Agrellite

 

Agrellite

 

Discovered in 1973;   IMA status: Valid (IMA approved 1976)

 

Chemistry

 

 

Chemical Formula:

NaCa2(Si4O10)F

 

Sodium Calcium Silicate Fluoride

Molecular Weight:

394.48 gm

Composition:

Sodium

5.83 %

Na

7.86 %

Na2O

 

Calcium

20.32 %

Ca

28.43 %

CaO

 

Silicon

28.48 %

Si

60.93 %

SiO2

 

Oxygen

40.56 %

O

 

 

 

Fluorine

4.82 %

F

4.82 %

F

 

  %

F

-2.03 %

 -O=F2

 

 

100.00 %

 

100.00 %

= TOTAL OXIDE

 

 

Classification

   

   

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/H.15-10

Nickel-Strunz 10th Ed. ID:

9.DH.75

 

9 : SILICATES (Germanates)
D : Inosilicates
H : Inosilicates with 4-periodic single chains, Si
4O12

Related to:

Litidionite Group

Synonyms:

IMA 1973-032

 

 

Crystal Data

   

   

Crystallography:

Triclinic - Pinacoidal

Crystal Habit:

Crystals elongated [001], to 10 cm; platy aggregates

Twinning:

None

 

 

Physical Properties

   

 

Cleavage:

[110] Perfect, [110] Perfect, [010] Poor

Fracture:

Irregular/Uneven, Conchoidal

Tenacity:

Brittle

Moh's Hardness:

5.5

Density:

2.902 (g/cm3)

Luminescence:

Fluoresces bright pink under LW UV and duller pink under SW UV.

Radioactivity:

Not Radioactive

 

 

Optical Properties

   

   

Color:

White, Gray-White, Greenish-White

Transparency:

Transparent to Translucent

Luster:

Vitreous, Pearly on cleavages

Refractive Index:

1.567 - 1.581  Biaxial ( - )

Birefringence:

0.0140

Dispersion:

Strong; r > v

 

 

Occurances

   

   

Geological Setting:

In pegmatite lenses and pods and in mafic gneisses in a regionally metamorphosed agpaitic alkalic rock complex (Villedieu Township, Canada).

Common Associations:

Biotite, Britholite, Calcite, Clinohumite, Fluorite, Galena, Gittinsite, Hiortdahlite, Miserite, Mosandrite, Norbergite, Phlogopite, Vlasovite, Zircon (Villedieu Township, Canada); Aegirine, Eudialyte, Miserite, Quartz (Wausau, Wisconsin, USA).

Type Locality:

Kipawa alkaline complex, Les Lacs-du-Témiscamingue, Témiscamingue, Abitibi-Témiscamingue, Québec, Canada

Year Discovered:

1973 (IMA approved 1976)

View mineral photos:

Agrellite Mineral Photos and Locations

 

 

Unusual Gem Categories

   

   

 

Fluorescent Gems

 

 

More Information

   

   

 

Mindat.org
Webmineral.com

 

 

Agrellite is a rare silicate mineral that is commonly found with Eudialyte and Aegirine. Its crystals are found as platy, blocky aggregates and so are not suitable for faceting but when combined with Eudialyte, can make beautiful cabochons.

Agrellite is named to honor Professor Stuart Olof Agrell (1913-1996), eminent petrologist, Cambridge University, Cambridge, England.

Agrellite is only found at a few locations including the Sheffield Lake complex, Kipawa River, Villedieu Township, Quebec, Canada; the Wausau complex, Marathon County, Wisconsin, USA; the Dara-i-Pioz massif, Alai Range, Tien Shan, Tajikistan; the Murun massif, southwest of Olekminsk, Yakutia, Russia.

Agrellite gems for sale:

We have not photographed our Agrellite gems. Please check back soon.

 


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