Nabalamprophyllite has a general formula of .
[ The name is given for its composition (Naba, meaning sodium, Na and barium, Ba) and relation to other lamprophyllite-group minerals. ]Lamprophyllite
Lamprophyllite (named for its lustrous cleavage) is a rare, but widespread mineral Ti-silicate mineral usually found in intrusive agpasitic igneous rocks. Yellow, reddish brown, Vitreous, Pearly.
Lamprophyllite formula is (Sr,Ba,K,Na)2Na(Na,Fe, ...
is a rare Ti-bearing silicate mineral usually found in intrusive igneous rocks.
Nabalamprophyllite is monoclinic, which means crystallographically, it contains three axes of unequal length and the angles between two of the axes are 90°, and one is less than 90°. It belongs to the space group P2/m.[ The mineral also has an ]orthorhombic
In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic lattices result from stretching a cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular prism with a r ...
polytype
In materials science, polymorphism describes the existence of a solid material in more than one form or crystal structure. Polymorphism is a form of isomerism. Any crystalline material can exhibit the phenomenon. Allotropy refers to polymorphism ...
(nabalamprophyllite-2O).[Sokolova, E., Hawthorne, F.C. (2008) From Structure Topology to Chemical Composition. IV. Titanium Silicates: The Orthorhombic Polytype of Nabalamprophyllite from the Lovozero Massif, Kola Peninsula, Russia. The Canadian Mineralogist, 46, 1323-1331.] This mineral belongs to the space group Pnmn. In terms of its optical properties, nabalamprophyllite is anisotropic
Anisotropy () is the property of a material which allows it to change or assume different properties in different directions, as opposed to isotropy. It can be defined as a difference, when measured along different axes, in a material's physic ...
which means the velocity of light varies depending on direction through the mineral. Its calculated relief is 1.86 - 1.87.[ Its color in plane polarized light is green-brown, and it is weakly ]pleochroic
Pleochroism (from Greek πλέων, ''pléōn'', "more" and χρῶμα, ''khrôma'', "color") is an optical phenomenon in which a substance has different colors when observed at different angles, especially with polarized light.
Backgroun ...
.
The mineral has only been found in Russia, usually in association with coarse-grained igneous rocks called pegmatites. The type localities are the Inagli alkaline–ultrabasic massif, Yakutia and the Kovdor alkaline–ultrabasic massif in the Kola Peninsula.
References
*N.V. Chukanov, M.M. Moiseev, I.V. Pekov, K.A. Lazebnik, R.K. Rastsvetaeva, N.V. Zayakina, G. Ferraris, G. Ivaldi (2004) Nabalamprophyllite Ba(Na,Ba){Na3Ti i2O2Si4O14OH,F)2}, a new layer titanosilicate of the lamprophyllite group from the Inagli and Kovdor alkaline-ultrabasic massifs, Russia. Zapiski Vseross. Mineral. Obshch., 133(1), 59–72 (in Russian, English abstract).
Sorosilicates
Barium minerals
Sodium minerals
Titanium minerals
Monoclinic minerals
Minerals in space group 10