Chemistry:Zircophyllite

From HandWiki
Zircophyllite
General
CategoryInosilicate
Formula
(repeating unit)
(K,Na)3(Mn,Fe2+)7(Zr,Ti)2Si8O24(O,OH,F)7
Strunz classification9.DC.05
Dana classification69.1.1.5
Crystal systemTriclinic
Crystal classPinacoidal (1)
(same H-M symbol)
Space groupP1
Identification
ColorBlack-brown
Crystal habitPlaty, micaceous
CleavagePerfect on {001}
FractureBrittle
TenacityBrittle
Mohs scale hardness4 - 4.5
|re|er}}Adamantine, vitreous
StreakLight brown
DiaphaneityTranslucent to opaque
Specific gravity3.34
Optical propertiesBiaxial (-)
Refractive indexnα = 1.708 nβ = 1.738 nγ = 1.747
Birefringenceδ = 0.039
PleochroismX = Y = dark yellow; Z = brown
2V angleMeasured: 62°, calculated: 56°
Common impuritiesHf,H2O
References[1][2][3]

Zircophyllite is a complex mineral, formula (K,Na)3(Mn,Fe)7(Zr,Ti,Nb)2Si8O24(OH,F)7. It crystallizes in the triclinic - pinacoidal crystal class as dark brown to black micaceous plates. It has perfect 001 cleavage, a Mohs hardness of 4 to 4.5 and a specific gravity of 3.34. Its indices of refraction are nα=1.708 nβ=1.738 nγ=1.747 and it has a 2V optical angle of 62°.

It occurs with natrolite in alkali pegmatites. It was discovered in 1972 in the Korgeredabinsh massif, Tuva, Russia and is named for its zirconium content and its relationship to astrophyllite. It is also known from the Mont Saint-Hilaire intrusive complex of Québec, Canada.

Zircophyllite is radioactive, but the radioactivity is barely detectable.[2]

References