The Rare Earths: Their Occurrence, Chemistry, and Technology

by Stanley Isaac Levy

Tetragonal; in globular aggregates.

Gr = 4·091. H = 7¹⁄₂. Dark green or brown; dull.

Gravel-tin of Japan.

Narsarsukite.

Na₆FeTi₂Si₁₂O₃₂F. TiO₂ = 14%.

Tetragonal. Habit tabular.

Gr = 2·75. H = 7-7¹⁄₂. Yellow to reddish-brown; pleochroic.

Plain of Narsarsuk, Greenland.

Neptunite.

(K,Na)₂(Fe,Mg,Ca,)₂(Ti,Si)₄O₁₂. TiO₂ = 18%.