Wairakite - Ca(Si4Al2)O12 * 2H2OF

Wairakite was first discovered by Steiner in 1955 in rocks ejected by steam from drill holes in Wairakei geothermal field (New Zeland). Wairakite is a zeolite mineral with an analcime structure. Except for a few deep-sea occurrences, wairakite comes from environments that have or had temperatures above 200°C. Wairakite is common in active or inactive geothermal systems and in some low-grade metamorphic aureoles, especially where associated with epizonal plutons.

Optical properties:
• Form: From fibrous to subhedral trapezohedral crystals, also as incrustation.
• Color: Colourless.
• Relief: Moderate.
• Birefringence: Very low.


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Snow-white wairakite crystals. Katashina Village, Gunma Prefecture, Japan. Image from RRUFF


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Snow-white wairakite crystals. Katashina Village, Gunma Prefecture, Japan. Image from RRUFF



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
wairakite(1).jpg

Aegirine (green) crystals surrounded by wairakite crystals in a syenite from Mont Saint-Hilaire, Canada. PPL image, 2x (Field of view = 7mm)		 wairakite(2).jpg

Aegirine crystals surrounded by wairakite crystals (with gray-white birefringence) in a syenite from Mont Saint-Hilaire, Canada. XPL image, 2x (Field of view = 7mm)		 wairakite(3).jpg

Aegirine (green) crystals surrounded by wairakite crystals in a syenite from Mont Saint-Hilaire, Canada. PPL image, 2x (Field of view = 7mm)
wairakite(4).jpg

Aegirine crystals surrounded by wairakite crystals (with gray-white birefringence) in a syenite from Mont Saint-Hilaire, Canada. XPL image, 2x (Field of view = 7mm)		 wairakite(5).jpg

Aegirine (green) crystals surrounded by wairakite crystals in a syenite from Mont Saint-Hilaire, Canada. PPL image, 2x (Field of view = 7mm)		 wairakite(6).jpg

Aegirine crystals surrounded by wairakite crystals (with gray-white birefringence) in a syenite from Mont Saint-Hilaire, Canada. XPL image, 2x (Field of view = 7mm)
wairakite(12).jpg

Aegirine (green) crystals surrounded by wairakite crystals in a syenite from Mont Saint-Hilaire, Canada. PPL image, 2x (Field of view = 7mm)		 wairakite(13).jpg

Aegirine crystals surrounded by wairakite crystals (with gray-white birefringence) in a syenite from Mont Saint-Hilaire, Canada. XPL image, 2x (Field of view = 7mm)		 wairakite(11).jpg

Aegirine crystals surrounded by wairakite crystals (with gray-white birefringence) in a syenite from Mont Saint-Hilaire, Canada. XPL image, 2x (Field of view = 7mm)
wairakite(14).jpg

Aegirine crystals surrounded by wairakite crystals (with gray-white birefringence) in a syenite from Mont Saint-Hilaire, Canada. XPL image, 10x (Field of view = 2mm)		 wairakite(15).jpg

Aegirine crystals surrounded by wairakite crystals (with gray-white birefringence) in a syenite from Mont Saint-Hilaire, Canada. XPL image, 10x (Field of view = 2mm)		 wairakite(16).jpg

Aegirine crystals surrounded by wairakite crystals (with gray-white birefringence) in a syenite from Mont Saint-Hilaire, Canada. XPL image, 10x (Field of view = 2mm)
wairakite(28).jpg

Aegirine crystals surrounded by wairakite crystals (with gray-white birefringence) in a syenite from Mont Saint-Hilaire, Canada. XPL image, 10x (Field of view = 2mm)		 wairakite(29).jpg

Aegirine crystals surrounded by wairakite crystals (with gray-white birefringence) in a syenite from Mont Saint-Hilaire, Canada. XPL image, 10x (Field of view = 2mm)		 wairakite(31).jpg

Aegirine crystals surrounded by wairakite crystals (with gray-white birefringence) in a syenite from Mont Saint-Hilaire, Canada. XPL image, 10x (Field of view = 2mm)
wairakite(20).jpg

Aegirine crystals surrounded by wairakite crystals (with gray-white birefringence) in a syenite from Mont Saint-Hilaire, Canada. XPL image, 10x (Field of view = 2mm)		 wairakite(22).jpg

Aegirine crystals surrounded by wairakite crystals (with gray-white birefringence) in a syenite from Mont Saint-Hilaire, Canada. XPL image, 10x (Field of view = 2mm)		 wairakite(25).jpg

Aegirine crystals surrounded by wairakite crystals (with gray-white birefringence) in a syenite from Mont Saint-Hilaire, Canada. XPL image, 10x (Field of view = 2mm)
wairakite(23).jpg

Aegirine (green) crystal surrounded by wairakite crystals in a syenite from Mont Saint-Hilaire, Canada. PPL image, 10x (Field of view = 2mm)		 wairakite(24).jpg

Aegirine (green) crystal surrounded by wairakite crystals (with gray-white birefringence) in a syenite from Mont Saint-Hilaire, Canada. XPL image, 10x (Field of view = 2mm)		 wairakite(19).jpg

Wairakite crystals (with gray-white birefringence) in a syenite from Mont Saint-Hilaire, Canada. XPL image, 10x (Field of view = 2mm)
wairakite(21).jpg

Wairakite crystals (with gray-white birefringence) in a syenite from Mont Saint-Hilaire, Canada. XPL image, 10x (Field of view = 2mm)		 wairakite(27).jpg

Wairakite crystals (with gray-white birefringence) in a syenite from Mont Saint-Hilaire, Canada. XPL image, 10x (Field of view = 2mm)		 wairakite(30).jpg

Wairakite crystals (with gray-white birefringence) in a syenite from Mont Saint-Hilaire, Canada. XPL image, 10x (Field of view = 2mm)