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Formanite-(Y)

Year of discovery: 1944 (Cooglegong pegmatite, Australia), 2005 (Japan)

Locality list: A locality of formanite-(Y)

• YTaO₄
• Y(Ta,Nb)O₄
• [Y³⁺][TaO₄]^3-

• Class: Fergusonite group
• Class: Tantalate

• Polymorph: Yttrotantalite-(Y) (Monoclinic), Iwashiroite-(Y) (Monoclinic), 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 brown
• Streak: Brown
• Luster: Vitreous
• Diaphaneity: Opaque

• Cleavage: Indistinct on {111} (4 plane)
• Hardness: 5.5-6.5
• Density: 7.0

• System: Tetragonal
• Group: 4/m, I4₁/a
• Lattice: a=7.8, c=11.4