Yellow crystals of tisinalite a mineral that it is only known from Russia, in a contrasting white matrix. From Koashva Mountain, Khibiny Massif, Murmansk Oblast, Russian Federation. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Tisinalite
Tisinalite is an IMA-recognized mineral species in the silicate class, with the chemical formula Na₃Mn²⁺TiSi₆O₁₅(OH)₃.
It crystallizes in the hexagonal crystal system (space group P-3). It is a member of the Lovozerite-Zirsinalite–Lovozerite structural group.
Key properties: Mohs hardness 5; specific gravity 2.66–2.69; Vitreous luster; optically uniaxial.
IMA symbol Tis, IMA status: approved, named in 1979.
Formed by the hydrothermal alteration of lomonosovite and barytolamprophyllite in alkalic pegmatites in a differentiated alkalic massif.
It is found associated with Koashvite, shcherbakovite, lamprophyllite.
The name refers to TItanium, SIlicon, and sodium, NAtrium, in the composition.