Greasy dull white crystals of the extremely rare Ca-Y-Th mineral Saryarkite-(Y) from the TL and only known locality worldwide: Akkuduk, Mointy Railway Station, Shet, Karaganda Oblast, Kazakhstan. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Saryarkite-(Y)
Saryarkite-(Y) is an IMA-recognized mineral species in the silicate class, with the chemical formula Ca(Y,Th)Al₅(SiO₄)₂(PO₄)₂(OH)₇·6H₂O.
It crystallizes in the tetragonal crystal system.
Key properties: Mohs hardness 3.5–4; specific gravity 3.07–3.15; Dull to greasy luster; optically uniaxial.
IMA symbol Syk-Y, IMA status: approved, named in 1964.
Found in Devonian propylitized felsic effusives and in altered granitic rocks in association with quartzites.
It is found associated with Mica, alunite, andalusite, huttonite, barite, molybdenite, pyrite, hematite, hydrous iron oxides.
The name comes from Saryarka, Kazakh name for the steppes area of central Kazakhstan, and for its high yttrium content.