Zinnwaldite - KLiFe2+Al(AlSi3O10)(F,OH)2

Named after its discovery locality at Zinnwald (now Cìnovec), on the border between Germany and the Czech Republic. Zinnwald was named for its tin deposits. Zinn means ‘tin’ in German. That doesn’t mean that zinnwaldite contains tin but zinnwaldite is often associated with cassiterite (one of the principal ore of tin).

The IMA (International Mineralogical Association) status is as a series between siderophyllite (KFe2Al(Al2Si2)O10(F,OH)2) and polylithionite (KLi2AlSi44O10(F,OH)2) and not considered a valid mineral species.

Zinnwaldite is a pneumatolytic mineral occurring in cassiterite and topaz-bearing pegmatites, greisens and quartz veins often associated with tin ore deposits. It is commonly associated with topaz, cassiterite, wolframite, lepidolite, spodumene, beryl, tourmaline, and fluorite.

Optical Properties:
Color: Colourless, can be pale-coloured with a weak pleochroism (brownish-grey).
Habit: Micaceous.
Interference colors: Medium-high birefringence (bright interference colours of the 2nd order).


Bibliography



• Deer, W.A., Howie, R.A., Zussman, J. (1998) Rock-forming Minerals.
• Nesse, William D., 1986, Introduction to Optical Mineralogy: New York, Oxford University Press




Photo
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Zinnwaldite (micaceous habit), topaz (high relief, colorless) and quartz in a greisen. Zinnwald, Saxony, Germany. PPL image, 1x (Field of view = 9mm)
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Zinnwaldite (high interference colors), topaz (I order gray) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 1x (Field of view = 9mm)
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Zinnwaldite (micaceous habit), topaz (high relief, colorless) and quartz in a greisen. Zinnwald, Saxony, Germany. PPL image, 1x (Field of view = 9mm)
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Zinnwaldite (high interference colors), topaz (I order gray) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 1x (Field of view = 9mm)
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Zinnwaldite (micaceous habit), topaz (high relief, colorless) and quartz in a greisen. Zinnwald, Saxony, Germany. PPL image, 1x (Field of view = 9mm)
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Zinnwaldite (high interference colors), topaz (I order gray) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 1x (Field of view = 9mm)
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Zinnwaldite (micaceous habit) and quartz in a greisen. Zinnwald, Saxony, Germany. PPL image, 2x (Field of view = 7mm)
greisen(36).jpg

Zinnwaldite (high interference colors) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 2x (Field of view = 7mm)
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Zinnwaldite (micaceous habit) and quartz in a greisen. Zinnwald, Saxony, Germany. PPL image, 2x (Field of view = 7mm)
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Zinnwaldite (micaceous habit) and quartz in a greisen. Zinnwald, Saxony, Germany. PPL image, 2x (Field of view = 7mm)
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Zinnwaldite (high interference colors) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 2x (Field of view = 7mm)
greisen(46).jpg

Zinnwaldite (micaceous habit) and quartz in a greisen. Zinnwald, Saxony, Germany. PPL image, 2x (Field of view = 7mm)
greisen(47).jpg

Zinnwaldite (high interference colors) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 2x (Field of view = 7mm)
greisen(63).jpg

Zinnwaldite (high interference colors) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 2x (Field of view = 7mm)
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Zinnwaldite (high interference colors) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 2x (Field of view = 7mm)
greisen(68).jpg

Zinnwaldite (high interference colors) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 10x (Field of view = 2mm)
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Zinnwaldite (high interference colors) in a greisen. Zinnwald, Saxony, Germany. XPL image, 10x (Field of view = 2mm)
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Zinnwaldite (high interference colors) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 10x (Field of view = 2mm)
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Zinnwaldite (high interference colors) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 10x (Field of view = 2mm)
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Zinnwaldite (high interference colors) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 10x (Field of view = 2mm)
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Zinnwaldite (high interference colors) in a greisen. Zinnwald, Saxony, Germany. XPL image, 10x (Field of view = 2mm)