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

• Cox et al. (1979): The Interpretation of Igneous Rocks, George Allen and Unwin, London.
• Howie, R. A., Zussman, J., & Deer, W. (1992). An introduction to the rock-forming minerals (p. 696). Longman.
• Le Maitre, R. W., Streckeisen, A., Zanettin, B., Le Bas, M. J., Bonin, B., Bateman, P., & Lameyre, J. (2002). Igneous rocks. A classification and glossary of terms, 2. Cambridge University Press.
• Middlemost, E. A. (1986). Magmas and magmatic rocks: an introduction to igneous petrology.
• Shelley, D. (1993). Igneous and metamorphic rocks under the microscope: classification, textures, microstructures and mineral preferred-orientations.
• Vernon, R. H. & Clarke, G. L. (2008): Principles of Metamorphic Petrology. Cambridge University Press.

Photo
Zinnwaldite (micaceous habit), topaz (high relief, colorless) and quartz in a greisen. Zinnwald, Saxony, Germany. PPL image, 1x (Field of view = 9mm)	Zinnwaldite (high interference colors), topaz (I order gray) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 1x (Field of view = 9mm)	Zinnwaldite (micaceous habit), topaz (high relief, colorless) and quartz in a greisen. Zinnwald, Saxony, Germany. PPL image, 1x (Field of view = 9mm)
Zinnwaldite (high interference colors), topaz (I order gray) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 1x (Field of view = 9mm)	Zinnwaldite (micaceous habit), topaz (high relief, colorless) and quartz in a greisen. Zinnwald, Saxony, Germany. PPL image, 1x (Field of view = 9mm)	Zinnwaldite (high interference colors), topaz (I order gray) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 1x (Field of view = 9mm)
Zinnwaldite (micaceous habit) and quartz in a greisen. Zinnwald, Saxony, Germany. PPL image, 2x (Field of view = 7mm)	Zinnwaldite (high interference colors) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 2x (Field of view = 7mm)	Zinnwaldite (micaceous habit) and quartz in a greisen. Zinnwald, Saxony, Germany. PPL image, 2x (Field of view = 7mm)
Zinnwaldite (micaceous habit) and quartz in a greisen. Zinnwald, Saxony, Germany. PPL image, 2x (Field of view = 7mm)	Zinnwaldite (high interference colors) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 2x (Field of view = 7mm)	Zinnwaldite (micaceous habit) and quartz in a greisen. Zinnwald, Saxony, Germany. PPL image, 2x (Field of view = 7mm)
Zinnwaldite (high interference colors) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 2x (Field of view = 7mm)	Zinnwaldite (high interference colors) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 2x (Field of view = 7mm)	Zinnwaldite (high interference colors) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 2x (Field of view = 7mm)
Zinnwaldite (high interference colors) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 10x (Field of view = 2mm)	Zinnwaldite (high interference colors) in a greisen. Zinnwald, Saxony, Germany. XPL image, 10x (Field of view = 2mm)	Zinnwaldite (high interference colors) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 10x (Field of view = 2mm)
Zinnwaldite (high interference colors) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 10x (Field of view = 2mm)	Zinnwaldite (high interference colors) and quartz in a greisen. Zinnwald, Saxony, Germany. XPL image, 10x (Field of view = 2mm)	Zinnwaldite (high interference colors) in a greisen. Zinnwald, Saxony, Germany. XPL image, 10x (Field of view = 2mm)