Cancrinite - Ca2Na6Al6O6(CO3)2*2H2O

Cancrinite is a member of the cancrinite-vishnevite family with the formula Ca2Na6Al6O6(CO3)2*2H2O. It is classed as a member of the feldspathoid group of minerals.
Found originally in 1839 in the Ural Mountains, it is named after Georg von Cancrin, a Russian minister of finance.

Cancrinite is a rare mineral and occurs in alkaline undersaturated magmatic rocks. it form columnar to needle-shaped crystals but typically granular. In the presence of high CO2 partial pressures cancrinite con form pseudomorph after Nepheline in alkaline rocks.

Optical properties:
Form: Columnar or needle-shaped crystals.
Cleavage: Perpendicular to the long axis.
Color: Colorless in thin section.
Extinction: Straight.
Birefringence: High, from yellow to violet.

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Brown cancrinite crystals from Cancrinite Hill, Ontario, Canada.




Bibliography



• Deer, W.A., Howie, R.A., Zussman, J. (1998) Rock-forming Minerals.
• Optical Mineralogy : The Nonopaque Minerals by Phillips / Griffen
• E. WM. Heinrich (1956): Microscopic Petrografy. Mcgraw-hill book company,inc
Stephen. A. Nelson


Photo
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Cancrinite (high interference colors) in a cancrinite-pegmatite from Punkaruaiv, Lovozero, Kola, Russia. XPL image, 10x (Field of view = 2mm)
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Cancrinite (high interference colors) in a cancrinite-pegmatite from Punkaruaiv, Lovozero, Kola, Russia. XPL image, 10x (Field of view = 2mm)
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Cancrinite (high interference colors) in a cancrinite-pegmatite from Punkaruaiv, Lovozero, Kola, Russia. XPL image, 10x (Field of view = 2mm)
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Cancrinite (high interference colors) in a cancrinite-pegmatite from Punkaruaiv, Lovozero, Kola, Russia. XPL image, 10x (Field of view = 2mm)
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Cancrinite (high interference colors) in a cancrinite-pegmatite from Punkaruaiv, Lovozero, Kola, Russia. XPL image, 10x (Field of view = 2mm)
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Cancrinite (high interference colors) in a cancrinite-pegmatite from Punkaruaiv, Lovozero, Kola, Russia. XPL image, 10x (Field of view = 2mm)
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Cancrinite crystal in a Nepheline-pegmatite. XPL image, 10x (Field of view = 2mm)
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Aegirine crystal rimmed by cancrinite (high interference colros). XPL image, 2x (Field of view = 7mm)
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Aegirine crystal rimmed by cancrinite (high interference colros). XPL image, 2x (Field of view = 7mm)
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Granular aggregate of Cancrinite crystals in a Nepheline-pegmatite. XPL image, 2x (Field of view = 7mm)
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Cancrinite crystals in a Nepheline-pegmatite. XPL image, 10x (Field of view = 2mm)
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Colorless Cancrinite crystals in a Nepheline-pegmatite. PPL image, 10x (Field of view = 2mm)
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Granular aggregate of Cancrinite crystals in a Nepheline-pegmatite. XPL image, 10x (Field of view = 2mm)
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Cancrinite crystals in a Nepheline-pegmatite. XPL image, 10x (Field of view = 2mm)
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Cancrinite crystals in a Nepheline-pegmatite. XPL image, 10x (Field of view = 2mm)
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Cancrinite crystals in a Nepheline-pegmatite. XPL image, 10x (Field of view = 2mm)
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Colorless Cancrinite crystals in a Nepheline-pegmatite. PPL image, 10x (Field of view = 2mm)
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Cancrinite crystals in a Nepheline-pegmatite. XPL image, 10x (Field of view = 2mm)
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Cancrinite crystals in a Nepheline-pegmatite. XPL image, 10x (Field of view = 2mm)
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Colorless Cancrinite crystals and Aeginrine crystals in a Nepheline-pegmatite. PPL image, 10x (Field of view = 2mm)
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Cristalli Cancrinite attorno ad aegirina in una pegmatite a nefelina. Immagine a NX, 10x (lato lungo = 2mm).
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Colorless Cancrinite crystals and Aeginrine crystals in a Nepheline-pegmatite. PPL image, 10x (Field of view = 2mm)
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Cancrinite crystals on Nepheline. XPL image, 2x (Field of view = 7mm)
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Colorless Cancrinite crystals and Aeginrine crystals in a Nepheline-pegmatite. PPL image, 10x (Field of view = 2mm)
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Cancrinite crystals in a Nepheline-pegmatite. XPL image, 10x (Field of view = 2mm)
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Cancrinite crystals on Nepheline. XPL image, 2x (Field of view = 7mm)
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Cancrinite crystals on Nepheline. XPL image, 10x (Field of view = 2mm)
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Eudialite (gray) surrounded by sodalite (isotropic) inclusion in a Naujaite. Ilímaussaq, Greenland. XPL image, 2x (Field of view = 7mm)
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K-feldspar with sodalite (isotropic) inclusion. Sodalite is surrounded by cancrinite (high interference colors). Ilímaussaq, Greenland. XPL image, 2x (Field of view = 7mm)
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K-feldspar with sodalite (isotropic) inclusion. Sodalite is surrounded by cancrinite (high interference colors). Ilímaussaq, Greenland. XPL image, 2x (Field of view = 7mm)
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K-feldspar with sodalite (isotropic) inclusion. Sodalite is surrounded by cancrinite (high interference colors). Ilímaussaq, Greenland. XPL image, 2x (Field of view = 7mm)
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K-feldspar with sodalite (isotropic) inclusion. Sodalite is surrounded by cancrinite (high interference colors). Ilímaussaq, Greenland. XPL image, 2x (Field of view = 7mm)
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K-feldspar with sodalite (isotropic) inclusion. Sodalite is surrounded by cancrinite (high interference colors). Ilímaussaq, Greenland. XPL image, 2x (Field of view = 7mm)
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Cancrinite crystals (high interference colors) around sodalite (isotropic). Ilímaussaq, Greenland. XPL image, 10x (Field of view = 2mm)
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Cancrinite crystals (high interference colors) around sodalite (isotropic). Ilímaussaq, Greenland. XPL image, 10x (Field of view = 2mm)
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Cancrinite crystals (high interference colors). Ilímaussaq, Greenland. XPL image, 10x (Field of view = 2mm)