Lamprophyllite - (Na,Mn2+)3(Sr,Na)2(Ti,Fe3+)3(Si2O7)2O2(OH,O,F)2

Named after the Greek words lampro and phyllo, meaning "shining" and "leaf" respectively, in reference to the mineral’s lustrous, leaf-like sheets that make up its cleavage planes. Lamprophyllite is a rare, but widespread mineral in alkaline rocks. It was first described from Kola Peninsula, Russia. Lamprophyllite is a complex group of sorosilicates with the general chemical formula given as A2B4C2Si2O7(X)4, where the site A can be occupied by Sr, Ba, Na and K; B is occupied by Na, Ti, Fe, Mn, Mg and Ca. The site C is mainly occupied by Ti or Fe3+ and X includes the anions F-, OH- and O2-.

Optical properties:
Form: Flattened and elongated crystals, often as stellate clusters.
Cleavage: Micaceous.
Color: Dark brown, brownish yellow.
Pleochroism: From orange to yellow.
Birefringence: High.



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


Photo
lamprophyllite(1).jpg

Dark brown lamprophyllite, astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 10x (Field of view = 2mm)
lamprophyllite(3).jpg

Dark brown lamprophyllite, astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 10x (Field of view = 2mm)
lamprophyllite(4).jpg

Dark brown lamprophyllite, astrophyllite and aegirine crystals in a syenite from Eveslogchorr, Kola, Russia. XPL image, 10x (Field of view = 2mm)
lamprophyllite(8).jpg

Dark brown lamprophyllite, astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 10x (Field of view = 2mm)
lamprophyllite(9).jpg

Dark brown lamprophyllite, astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 10x (Field of view = 2mm)
lamprophyllite(10).jpg

Dark brown lamprophyllite, astrophyllite and aegirine crystals in a syenite from Eveslogchorr, Kola, Russia. XPL image, 10x (Field of view = 2mm)
lamprophyllite(13).jpg

Dark brown lamprophyllite, astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 10x (Field of view = 2mm)
lamprophyllite(5).jpg

Dark brown lamprophyllite, astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 20x (Field of view = 1mm)
lamprophyllite(6).jpg

Dark brown lamprophyllite, astrophyllite and aegirine crystals in a syenite from Eveslogchorr, Kola, Russia. XPL image, 20x (Field of view = 1mm)
lamprophyllite(7).jpg

Dark brown lamprophyllite, astrophyllite (brown-orange) and aegirine (green) crystals in a syenite from Eveslogchorr, Kola, Russia. PPL image, 20x (Field of view = 1mm)