Orthorhombic; in pyramids resembling those of Zircon.
Crystals are small, and covered with a thin yellow crust; they are intergrown with [Parisite] (q.v.)
Langesund Fiord, Norway.
Wiikite.
Titano-tantalo-silicate of Zr, Th, E, Fe, U, with Cb₂O₅, H₂O, etc. Cer = 2·5; Yttr = 7·6; Sc₂O₃ = 1·2; ThO₂ = 5·5; ZrO₂ + TiO₂ = 23·4%.
Perfectly amorphous.
G = 4·85. H = 6. Black; opaque; infusible.
Impilaks, Lake Ladoga, Finland.
Wöhlerite.
Silicate and columbate of Ca, Zr, Na; Si₁₀Zr₃Cb₂O₄₂F₃Ca₁₀Na₅? ZrO₂ = 15·2-22·7%. Cer, traces.