210 METALS. 



Dimetric. In prisms of eight, twelve, or more sides, 

 with pyramidal terminations, and often bent 

 as in the figure; a : a = 123° 8'. Crystals 

 often acicular, and penetrating quartz. Some- 

 times massive. Cleavage lateral, somewhat 

 listinct. 



Color reddish-brown to nearly red ; streak very pale • 

 rown. Luster submetallic -adamantine. Transparent to 

 opaque. Brittle. H=6— 6*5. Gr=4'15— 4-25. 



Composition : titanium 61, oxygen 39. Sometimes contains 

 iron, and has nearly a black color ; this variety is called 

 nigrine. Unaltered alone before the blowpipe. Forms a 

 hyacinth-red bead with borax. 



Dif. The peculiar subadamantine luster of rutile, and 

 brownish-red color, much lighter red in splinters, are striking 

 characters. It differs from tourmaline, idocrase, and augite, 

 by being unaltered when heated alone before the blowpipe ; 

 and from tin ore, in not affording tin with soda ; from sphene 

 in its crystals. 



Obs. Occurs imbedded in granite, gneiss, mica slate, 

 syenite, and in granular limestone. Sometimes associated 

 with, specular iron, as at the Grisons. Yrieix in France, 

 Castile, Brazil, and Arendal in Norway, are some of the 

 foreign localities. 



In the United States, it occurs in crystals in Maine, at 

 Warren; in New Hampshire, at Lyme and Hanover; in 

 Massachusetts, at Barre, Windsor, Shelburne, Leyden, Con- 

 way ; in Connecticut, at Monroe and Huntington ; in New 

 York, near Edenvilie, Warwick, Amity, at Kingsbridge, and 

 in Essex county at Gouverneur ; in the District of Columbia, 

 at Georgetown ; in North Carolina, in Buncombe county ; 

 in the gold district of Georgia. 



Uses. The specimens of limpid quartz, penetrated by long 

 acicular crystals, are often very elegant when polished. A 

 remarkable specimen of this kind was obtained at Han- 

 over, N. H., and less handsome ones are not uncommon. 

 Polished stones of this kind are called fleches d' amour (love's 

 arrows) by the French. 



Describe rutile. Of what does it consist? How is it distinguished 

 torn other minerals 1 What are its uses 1 



