The Rare Earths: Their Occurrence, Chemistry, and Technology

by Stanley Isaac Levy

Orthorhombic; isomorphous with [Samarskite] (q.v.).

G = 5·5-5·8. H = 5-6. Yellow to black.

Ytterby, Sweden; South Norway.

Zircon.

ZrSiO₄, with Fe, Th, etc., in traces. ZrO₂ = 61·0-70·0%.

Tetragonal; habit prismatic.

G = 4·68-4·70. varying considerably. H = 7¹⁄₂. Colour very variable.

Widely distributed as a rock mineral, in sands, etc.

Zirkelite.

(Ca,Fe)(Zr,Ti,Th)₂O₅, with E, U, Mg, etc. ZrO₂ = 48·9-52·9; ThO₂ = 0-7·3; TiO₂ = 14-15; E₂O₃ = 0-3%.