The Rare Earths: Their Occurrence, Chemistry, and Technology

by Stanley Isaac Levy

Orthorhombic; acicular.

G = 3·4. H = 6. Colourless; transparent.

South Greenland.

Mackintoshite.

Mixture of oxides, chiefly of Th and U; also Fe, Ca, Mg, Pb, Na, B, Ta, etc. Composition very complex. ThO₂ = 45·3; E₂O₃ = 1·9; ZrO₂ = 1%.

Tetragonal, resembling [thorite] (q.v.).

G = 5·42. H = 5¹⁄₂. Black; opaque.

Bluffton, Llano Co., Texas.

Malacone.

An altered [Zircon] (q.v.), with E, Ca, Fe, H₂O, etc. ZrO₂ = 47-67%.