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Yttrialite-(Y)
Year of discovery: 1889 (Baringer Hill, USA), 1938 (Japan)
Locality list: 10 localities of yttrialite-(Y)
- Y2Si2O7
- (Y,Th)2Si2O7
- [Y3+2][Si2O7]6-
- Polymorph: Keiviite-(Y) (Monoclinic)
- Y2 => K2Zr: Khibinskite
- Y2 => Na2Zr: Parakeldyshite, Keldyshite
- Color: Grayish green, Brown, Black
- Streak: Pale brown
- Luster: Greasy
- Diaphaneity: Translucent-Opaque
- Cleavage: No
- Hardness: 5.5
- Density: 4.6
- System: Monoclinic
- Group: 2/m, P21/m
- Lattice: a=7.3, b=8.1, c=5.0, β=108.5