The Rare Earths: Their Occurrence, Chemistry, and Technology

by Stanley Isaac Levy

Massive.

G = 4·515. H = 6. Pale dull green.

Llano Co., Texas.

Rutile.

Titanium dioxide; TiO₂ = 98-100%

Tetragonal; habit prismatic.

G = 4·18-4·25. H = 6-6¹⁄₂. Reddish-brown to black.

Very widely in Europe and America.

Samarskite.

R´´₃R´´´₂(Cb,Ta)₆O₂₁, where R´´ = Fe, Ca, UO₂; R´´´ = E. Cer = 1·2-6·4; Yttr = 4·72-21·2; ThO₂ + ZrO₂ → 7%.