The Rare Earths: Their Occurrence, Chemistry, and Technology

by Stanley Isaac Levy

Allanite (Orthite).

H₂O, 4R´´O, 3R´´´₂O₃, 6SiO₂, where R´´ = Ca, Fe´´, Be, and R´´´ = Al, Fe´´´, E. An epidote containing rare earths. Cer = 3·6-51 (usually 10-25); Yttr = 0-8 (usually < 3); ThO₂ = 0-3·5%.

Monoclinic; isomorphous with epidote.

G = 3·5-4·2. H = 5¹⁄₂-6. Brown to black; opaque.

Widely distributed in Greenland and Scandinavia.

Alvite (Anderbergite).

Silicate of Zr and E, with Ca, Mg, Be, Al, Cu, Zn, and aq. in small quantities. Cer → 3·98; Yttr → 22; ZrO₂ = 30·5-61·4%.

Tetragonal; optically isotropic. Pseudomorphous after zircon.

G = 3·3-4·3. H = 5-6. Yellowish brown; transparent.

Ytterby, Sweden; Arendal, Norway; various localities in N. America.