Sharp brown crystals of the very rare mineral shcherbakovite from the type locality: Rasvumtchorr, Khibiny, Kola, Russian Federation. — Photo: David Hospital · CC BY-SA 4.0
Shcherbakovite
Shcherbakovite is an IMA-recognized mineral species in the silicate class, with the chemical formula K₂NaTi₂O(OH)Si₄O₁₂.
It crystallizes in the orthorhombic crystal system (space group Imma). It is a member of the Batisite structural group.
Key properties: Mohs hardness 6.5; specific gravity 2.968; Vitreous, greasy on fracture surfaces luster; optically biaxial.
IMA symbol Sbk, grandfathered status — known before the IMA’s founding, named in 1954.
Very rare, in pegmatite in a differentiated alkalic massif as a hydrothermal pectolite- natrolite vein cutting leucite-normative kalsilite-nepheline rischorrite (Khibiny massif, Russia); in lamproite (Leucite Hills, Wyoming, USA).
It is found associated with Natrolite, manganoan pectolite, albite, potassic feldspar, astrophyllite, strontian fluorapatite, titanite (Khibiny massif, Russia); priderite, jeppeite.
The name refers to Academician Demitrii Ivanovich Shcherbakov (1893-1966), Russian mineralogist and geochemist, Institute of Geology of Ore Deposits, Petrology, Mineralogy, and Geochemistry, Moscow.