The Rare Earths: Their Occurrence, Chemistry, and Technology

by Stanley Isaac Levy

Monoclinic, very close to Johnstrupite.

G = 3·46. H = 5. Yellow, pleochroic; translucent.

Kangerdluarsuk, Greenland.

Risörite.

An yttria columbate, near Fergusonite, but with no U and considerable TiO₂; Yttr = 37; Cer = 2·9-4·0; TiO₂ = 6·5%.

No data yet determined. Isotropic.

G = 4·179. H = 5¹⁄₂. Yellowish brown.

Norway.

Rogersite.

Hydrated yttria columbate. Yttr = 60·12%. A weathered Samarskite?