Pale brown crystals of the rare mineral sitinakite from the type locality in Russia (Kukisvumchorr Mountains, Khibiny Massif, Murmansk Oblast, Russian Federation). Original material from the author. Ex.Dr.Hartel collection. — Photo: David Hospital · CC BY-SA 4.0
Sitinakite
Sitinakite is an IMA-recognized mineral species in the silicate class, with the chemical formula KNa₂Ti₄Si₂O₁₃(OH)·4H₂O.
It crystallizes in the tetragonal crystal system (space group P4_2/mcm).
Key properties: Mohs hardness 4.5; specific gravity 2.86; White streak; Vitreous luster; optically uniaxial.
IMA symbol Sit, IMA status: approved, named in 1989.
Found in hydrothermally altered portions of alkalic pegmatites in a differentiated alkalic massif.
It is found associated with Nepheline, natrolite, aegirine, microcline, apatite, vinogradovite.
The name refers to SIlicon; TItanium; sodium, NAtrium; and potassium, Kalium, in its composition.