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Iwashiroite-(Y)

Year of discovery: 2003 (Japan as the first occurence in the World)

Locality list: A locality of iwashiroite-(Y)

• YTaO₄
• Y(Ta,Nb)O₄
• [Y³⁺][TaO₄]^3-

• Class: Yttrotantalite group
• Class: Tantalate

• Polymorph: Yttrotantalite-(Y) (Monoclinic), Formanite-(Y) (Tetragonal), Takanawaite-(Y) (Monoclinic)

• Y => Bi: Bismutotantalite
• Y => Sb: Stibiotantalite

• Y₂ => MnSn; Wodginite
• Y₂ => FeSn; Ferrowodginite
• Y₂ => MnTi; Titanowodginite

• TaO₄ => VO₄: Wakefieldite-(Y)
• TaO₄ => NbO₄: Fergusonite-(Y), β-Fergusonite-(Y), Samarskite-(Y)

• Color: Dark reddish brown, Yellowish brown
• Streak: Pale brown
• Luster: Vitreous
• Diaphaneity: Translucent

• Cleavage: Good on {010} (1 plane), Imperfect on {001} (1 plane)
• Hardness: 6
• Density: 7.1

• System: Monoclinic
• Group: 2/m, P2/a
• Lattice: a=5.3, b=5.5, c=5.1, β=95.1

Etymology: Iwashiro, old county name of western Fukushima prefecture, Japan, where this mineral was discovered for the first time . The old county name of eastern Fukushima prefecture, Iwaki, is the etymology of Iwakiite.