The Rare Earths: Their Occurrence, Chemistry, and Technology

by Stanley Isaac Levy

Cubic; near to [Perovskite] (q.v.).

H = 5-6. Black. Transparent in flakes.

Lake Magad, E. Africa.

Uraninite.

Oxides of U (60-75%), with PbO₂, ThO₂, ZrO₂, E₂O₃, Fe₂O₃, etc. Cer. = 0-2·7; Yttr = 0-10·2; ThO₂ = 1·6-11·1; ZrO₂ = 0-8·1%.

Cubic, usually massive; alters to amorphous pitchblende.

G = → 6·4 (massive); → 9·7 (crystalline). H = 5¹⁄₂. Black; transparent in splinters.

Norway; Bohemia; Saxony; Cornwall; Carolina, etc.

Vietinghofite.

A hydrated ferruginous [samarskite] (q.v.). E₂O₃ = 8·2; ZrO₂ = 1·0%.