TITANIUM ORES. 209 



Tschefkinite. Resembles gadolinite. Color velvet-black. Luster 

 vitreous. Streak dark brown. H=5 — 55. Gr=45 — 46. It is a 

 eilico-titanate of cerium. GelatinizeB readily on heating in muriatic 

 acid. From thellmen Mountains, in Siberia. 



Polymignite is principally a titanate of zirconia, yttria, iron and ce- 

 rium. It has a black color, a brilliant submetallic luster within, a dark 

 brown streak, and a conchoidal fracture. Generally in slender striated 

 crystal?, secondaries to a rectangular prism. H=65. Gr=4-7— 4*9. 

 From Norway. Also, as observed by Prof. C. U. Shepard, from Bev- 

 erly, Mass. 



Polycrase is near polymignite. Massive, and in thin linear crystals, 

 of bright luster. Color black. Streak grayish-brown. H=55. Gr 

 =51. With orthite in Norway. 



Samarskite is a columbate of uranium, yttria and iron. Velvet- 

 black. H=5-5— 6. Gr=5'4— 5-7. From the Urals, also from North 

 Carolina. 



JEschynite. In crystals, black to brownish yellow ; luster resinous 

 to submetallic ; streak gray to yellowish brown or black. H=5 — 6. 

 Gr=49 — 51. A titanate of zirconia and cerium. From Miask in 

 the Urahv in feldspar with mica and zircon. 



Eutherfordite. Blackish brown, with a vitreo-resinous fracture and 

 no cleavage ; powder yellowish-brown. From the gold mines of Ruth- 

 erford Co., N. C, along with rutile, brookite. zircon and monazite. It 

 contains 585 per cent, of titanic acid with 10 per cent, of lime, and 

 perhaps cerium and yttrium. 



4. TITANIUM. 



Titanium occurs in nature combined with oxygen, forming 

 titanic acid or oxyd, and also in combinations with different 

 bases. It has not been met with native. 



The ores are infusible alone before the blowpipe, or nearly 

 so. Their specific gravity is between 3 and 4*5. With 

 salt of phosphorus, in the inner flame on charcoal, a globule 

 is obtained with some difficulty, which is violet blue when 

 cold. 



In the species called silico-titanates, that is, containing 

 silica and titanic acid, the titanic acid is a base. Titanium 

 and iron, and allied elements, are isomorphous, and analo- 

 gous oxyds replace one another. See author's System of 

 Min., 4th edition. 



How does titanium oecur? What is said of its ores ? 



