Astrophyllite - K₂NaFe²⁺₇Ti₂Si₈O₂₈(OH)₄F

Astrophyllite is one of a large group of silicate minerals which occurs as accessory minerals in alkaline igneous rocks. These minerals are characterized chemically by the presence of large amount of sodium, titanium, zirconium and often manganese, and the almost complete absence of aluminum and magnesium. Astrophyllite was first discovered in 1854 at Laven Island, Norway, and the name is from the Greek "astron" for "star" and "phyllon" for "leaf", in allusion to its habit of starburst-like sprays and micaceous cleavage. It is usually found in fissures and cavities in in alkaline igneous rocks.

Optical properties:
• Form: Bladed, acicular or tabular crystals.
• Cleavage: Perfect on (001) and poor on (100).
• Color: Bronze-yellow to gold-yellow, brown to reddish brown.
• Pleochroism: Strong, from deep orange-red to lemon-yellow.
• Birefringence: High.

Stellate aggregates of astrophyllite. Kirovsk, Russia

Stellate aggregates of astrophyllite. Kirovsk, Russia

Stellate aggregates of astrophyllite. Kirovsk, Russia

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
Astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (high interference colors) and aegirine crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)
Astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (high interference colors) and aegirine crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)
Astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (high interference colors) and aegirine crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)
Astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)
Astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (high interference colors) and aegirine crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)
Astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)
Astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (high interference colors) and aegirine crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)
Astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)
Astrophyllite (high interference colors) and aegirine crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (high interference colors) and aegirine crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)
Astrophyllite (brown-orange), aegirine (green) and eudyalite (pink) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (brown-orange), aegirine (green) and eudyalite (pink) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (brown-orange), aegirine (green) and eudyalite (pink) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)
Astrophyllite (brown-orange), aegirine (green) and eudyalite (pink) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (brown-orange), aegirine (green) and eudyalite (pink) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (brown-orange), aegirine (green) and eudyalite (pink) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)
Astrophyllite (brown-orange), aegirine (green) and eudyalite (pink) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)	Astrophyllite (brown-orange), aegirine (green) and eudyalite (pink) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 2x (Field of view = 7mm)