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Category Inosilicate
(repeating unit)
Strunz classification 9.DC.05
Dana classification
Crystal system Triclinic
Crystal class Pinacoidal (1)
(same H-M symbol)
Space group P1
Color Black-brown
Crystal habit Platy, micaceous
Cleavage Perfect on {001}
Fracture Brittle
Tenacity Brittle
Mohs scale hardness 4 - 4.5
Luster Adamantine, vitreous
Streak Light brown
Diaphaneity Translucent to opaque
Specific gravity 3.34
Optical properties Biaxial (-)
Refractive index nα = 1.708 nβ = 1.738 nγ = 1.747
Birefringence δ = 0.039
Pleochroism X = Y = dark yellow; Z = brown
2V angle Measured: 62°, calculated: 56°
Common impurities Hf,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]