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Cerium

oxide, occurs, gravity and specific

CERIUM, a metal not found pure in nature. It occurs in several minerals, of which the following are the most remarkable I. Ccrite, found near Riddarhittan, in Sweden. It occurs amor phous. Its colour is pale dull red, sometimes grayish. and its streak is white ; its lustre is resinous, slightly translucent, and sufficiently hard to give sparks with steel, or 5'5. Specific gravity, 4'912.

According to Ilitsinger it consists of— Silica 18 Peroxide of Cerium . . . . Peroxide of Iron . . . . . 2 Limo . . . . . . . P25 Water and Carbonic Acid . . . In the opinion of Dr. Thomson it is a hydrous silicatcd peroxide of Cerium.

2. Celine, Tound as above, occurs massive and in imperfect crystals. Colour brownish-black, streak brownish-gray, opaque, with an imper fect metallic lustre. Hardness to 6-0. Specific gravity, 4173 Composition according to Bcrzelius : Silica 30'07 Oxide of Cerium . . . . . 2819 Oxide of Iron 20'7 Oxide of Copper . . . . . 0'87 Alumina 1P07 Limo . ..... . 9'12 Volatile Matter 0'4 100'42 3. Allanitc, found at Alluk, East Greenland. It occurs massive, and crystallised in the form of a prism. Fracture imperfect conchoidal. It is opaque, with an imperfect metallic lustre.

Colour brownish-black, streak greenish-gray. Hardness, 6'0. Specific gravity, 4. It is composed, according to Stromeycr, of— Silica . . . . . . . . 'Protoxide of Cerium . . . . . .21'6 Protoxidc of Iron Protoxide of Manganese . . . 0.404 Alumina 15.226 Limo . ..... . Water 3 4. Mona:ite, found near Slatoust, Russia ; also in the United States, where it occurs in small brown crystals, disseminated through mica slate ; at Norwich, Connecticut ; at Chester, Connecticut ; and York Town, New York. It is brittle, has a hardness of 5, and specific gravity of to 51. It is composed of— Oxide of Cerium Oxide of Lantanium . . . . 23'04 Thoria . . . . . . Phosphoric Acid Oxide of Tin . . . . . . 2'01 Protoxido of Manganese . . . . . 1.09 Lime 1'07 99'21 5. Cryptolite is a phosphate of the Oxide of Cerium in minute prisms. It is found with the apatite of Arendal, Norway. It has a pale wine-yellow colour. It has a specific gravity of 4'6.

Orthite is another mineral with Cerium [OwriirrEi ; se also are Yttro ccrite [YTTBOCERITE] and Pyrochlore [PYROCIILORE