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Ishikawaite

Year of discovery: 1922 (Japan as the first occurence in the World)

Locality list: 5 localities of ishikawaite

• UFeNb₂O₈
• (U,Fe)NbO₄
• [U⁴⁺][Fe²⁺][(NbO₄)₂]^6-

• Class: Niobate
• Radioactive: Very strong

• Polymorph: Petscheckite (Hexagonal)

• Fe => Y: Yttrocolumbite-(Y)

• UFe => Ce₂: β-Fergusonite-(Ce)
• UFe => Nd₂: β-Fergusonite-(Nd)
• UFe => Ca₂: Calciosamarskite
• UFe => Y₂: Samarskite-(Y), Fergusonite-(Y), β-Fergusonite-(Y)
• UFe => Yb₂: Samarskite-(Yb)

• U⁴⁺Fe => U⁶⁺: Liandratite

• Color: Black
• Streak: Dark brown
• Luster: Waxy
• Diaphaneity: Opaque

• Cleavage: No
• Hardness: 5-6
• Density: 6.3

• System: Orthorhombic, Amorphous
• Lattice: a=5.6, b=9.9, c=5.2, β=93.9

Etymology: Ishikawa district, Fukushima prefecture, Japan, where this mineral was discovered for the first time.