The Rare Earths: Their Occurrence, Chemistry, and Technology

by Stanley Isaac Levy

Orthorhombic.

G = 4·39-4·98. H = 6. Dark brown to black.

Norway; France.

Pyrochlore.

A columbate of Ca and E, with Th, Fe, Ti, F, etc. E₂O₃ → 18; TiO₂ = 5-14%.

Cubic.

G = 4·2-4·36. H = 5-5¹⁄₂. Dark brown.

Scandinavia; the Urals; Tasmania, etc.

Pyrophanite.

MnTiO₃, with traces of SiO₂. TiO₂ = 50-53%.