PART I. _occurrence of the Rare Earths_

OCCURRENCE OF THE RARE EARTHS

CHAPTER PAGE

I. THE NATURE OF THE MINERALS AND THEIR MODE OF OCCURRENCE 1

II. THE SILICATES 30

(a) Silicates of Yttrium and Cerium Metals--Cerite; Gadolinite, Glowing of Minerals; Allanite, Hellandite, Thalénite and Thortveitite; etc.

(b) Silicates of Thorium and Zirconium--Thorite, Zircon, Naegite; etc.

(c) Mixed Silicates--Eudialyte, Beckelite; etc.

III. THE TITANO-SILICATES AND TITANATES 52

(a) Titano-silicates--Yttrotitanite, Titanite; etc.

(b) Titanates--Yttrocrasite, Delorenzite, Ilmenite; etc.

IV. THE TANTALO-COLUMBATES 60

(a) Containing no Titanium Dioxide--Samarskite (Annerödite), Plumboniobite, Yttrotantalite, Fergusonite, Sipylite; etc.

(b) Containing Titanium Dioxide--Æschynite; the isodimorphous series Euxenite, Polycrase, Blomstrandine, Priorite; Risörite, Wiikite; etc.

V. THE OXIDES AND CARBONATES 72

(a) Oxides--Uraninite, Thorianite, Baddeleyite; Rutile, Anatase and Brookite; etc.

(b) Carbonates--Lanthanite; Parisite (Synchisite), Cordylite; etc.

VI. THE PHOSPHATES AND HALIDES 82

(a) Phosphates--Monazite, Xenotime (Hussakite); etc.

(b) Halides--Yttrocerite, Yttrofluorite; etc.

VII. THE MONAZITE SANDS 90

VIII. RADIOACTIVITY OF THE MINERALS 99