Zinnwaldite



This article is about the mineral. For the color, see Zinnwaldite (color).
Zinnwaldite

General
CategoryPhyllosilicate mineral
Chemical formulaKLiFeAl(AlSi3)O10(OH,F)2
Identification
ColorLight brown to yellowish- or greenish-white
Crystal habitMicaceous, platey scaly masses, pseudo-hexagonal phenocryst tablets
Monoclinic
TwinningOn composition plane {001}, twin axis [310].
CleavagePerfect basal {001}
FractureUneven
TenacityLaminae flexible, elastic.
Mohs Scale hardness3.5 - 4.0
LusterPearly to vitreous
Refractive indexnα = 1.565 - 1.625 nβ = 1.605 - 1.675 nγ = 1.605 - 1.675
Optical PropertiesBiaxial (-) 2V = 30°
Birefringence0.040 - 0.050
Pleochroismdistinct
StreakWhite
Specific gravity2.9 - 3.1
DiaphaneityTransparent to translucent

Zinnwaldite, mica group.

It occurs in fluorite.

It was first described in 1845 in Zinnwald (http://de.wikipedia.org/wiki/Zinnwald), Germany.

References

  • Handbook of Mineralogy
  • Webmineral data
  • Mindat
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Zinnwaldite". A list of authors is available in Wikipedia.