428 



DESCRIPTIVE MINERALOGY. 



ANATASE. 



[From the Greek, signifying elevated \ in allusion to the height of the pyramids of the octahedral 



crystals.] 



Anatase. Umiy, Bcudant, Phillips and Sliepard. — Octaedral Oxide of Titanium. Ckavcland. — Protoxide 

 of Titanium. TVumism. — Pyramidal Titanium. Jameson. — Pyramidales Titan-Erz. Mohs. 



510. 



Description. Colour blue and brown of various shades ; by trans- 

 mitted light, it is greenish yellow. Streak white. It occurs regu- 

 larly crystallized. The primary form is an octahedron with a square 

 base. Fig. 510. P on P and P' on P' 98° 5' ; P on P' 136° 47'. 

 Cleavage parallel to the primary faces, and perpendicular to the axis. 

 Fracture conchoidal, scarcely observable. Lustre splendent and ada- 

 mantine. Translucent and transparent. Brittle. Hardness from 5 . 5 

 to 6.0. Specific gravity from 3 . 80 to 3 . 90. Alone before the blow- 

 pipe, it is infusible ; with soda, it forms a dull yellow globule, which 

 becomes white on cooling. 



Composition. It is supposed to be a pure oxide of titanium. For- 

 mula TiO. 



Geological Situation. It occurs in small irregular veins in pri- 

 mitive rocks, as granite and mica slate, where it accompanies albite, 

 axinite, quartz, etc. It is still a rare mineral. 



LOCALITY. 



There sometimes accompanies the specimens of native titanium found in the slags of 

 Orange county, a coating of a dark blue or purple colour, wliich may be the oxide of tita- 

 nium. Although the quantity heretofore observed is quite too small for a chemical examina- 

 tion, the circumstances under which it is found seem to warrant the opinion which has been 

 advanced. 



Titane Oxide. Hafni. 

 Titanic Acid. 

 Fig. 511. 



RUTILE. 



— Red Oxide of Titanium. Claivclaiul. — Rutile. Phillips, Shepard and Bcudant. — 

 Thomson. — Peritomous Titanium Ore. Jameson. — Peritomes Titan-Erz. Mohs. 



Description. Colour red, brown, yellow, and sometimes nearly 

 velvet-black. Streak pale brown. It occurs regularly crystallized ; 

 also massive, disseminated, in angular grains and flakes. Primary 

 form a right square prism. Fig. 511. In some crystals the lateral 

 edges are replaced by tangent planes ; in others, by two planes. The 

 prism is terminated by a four or eight-sided pyramid, and is sometimes 

 geniculated and striated longitudinally. Cleavage perfect parallel with 

 M ; interrupted parallel with / (see Fig 513). Fracture conchoidal. 

 Lustre adamantine, inclining to metallic. Transparent to opaque. 



