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Arfvedsonite crystal - click for larger pic
Arfvedsonite crystal
© Doug Merson

Arfvedsonite crystals - click for larger pic
Arfvedsonite crystals
© Doug Merson

Arfvedsonite crystals - click for larger pic
Arfvedsonite crystal
© Stephan Wolfsried

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Home > Mineral Descriptions > Arfvedsonite - (3 Photos)



Arfvedsonite
Na2(Fe+2,Mg)4Fe+3Si8O22(OH)2

     Arfvedsonite is a common amphibole at Mont Saint-Hilaire. It can be found in pegmatite dikes up to 20cm and as black prisms in marble xenoliths. Fresh crystals are black and display a vitreous to dull luster, while in altered pegmatites the crystals may be partially altered or etched. Magnesio-arfvedsonite and fluoro-magnesio-arfvedsonite are also found at MSH, they are indistinguishable from each other without chemical analysis.

PHYSICAL CHARACTERISTICS:

Color is dark green to gray, black.
Luster is vitreous to dull.
Diaphaneity is opaque.
Crystal System is monoclinic; C2/m.
Crystal Habits include excellent prismatic crystals, prisms and pitted
   somewhat fibrous crystals.
Cleavage: {110} is perfect.
Fracture is uneven to subconchoidal.
Hardness is 5 to 6.
Specific Gravity is approximately 3.1 g/cm3.
Streak is dark blueish grey.
Associated Minerals include chkalovite, erdite, kogarkoite,
   makatite, natrophosphate, rasvumite, revdite, sazhinite-(Ce),    sidorenkite, thalcusite, tugtupite, vitusite-(Ce).
Distinguishing Features: Crystal habit.
Origin: Named in 1923 after Johan A. Arfvedson (1792-1841), Swedish    chemist.

CLASSIFICATION:

Dana System
# 66.1.3c.9

Strunz Classification
# VIII/F.8-100

REFERENCES:
MinRec 21:296 (1990), CanMin 34:1011 (1996), Dana 8:1364-1365 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

MSH
¤¤¤

PE
¤¤

AP
¤¤

MX
¤¤

SS
--

MC
--

HF
--

BR
--

SX
--

FR
--

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