THE NONMETALLIC MINERALS. 245 



The raw ocher (that is, ocher not roasted), of a light-yellow color, 

 was at one time in great demand, particularly throughout New Eng- 

 land, for painting floors. 



The value of the prepared material is but a few cents a pound. 



BIBLIOGRAPHY. 



FRANK A. HILL. Report on the Metallic Paint Ores along the Lehigh River. 



Annual Report, Pennsylvania Geological Survey, 1886, pt. 4, pp. 1386-1408. 



This is an important paper, giving position of ore beds, methods of mining 

 and manufacture. 

 CONRAD E. HESSE. The Paint Ore Mines at Lehigh Gap. 



Transactions of the American Institute of Mining Engineers, XIX, 1890, p. 321. 



7. ILMENITE; MENACCANITE; OB TITANIC IRON. 



Composition FeTiO 3 ,= oxygen, 31.6; titanium, 31.6; iron, 36.8; 

 hardness, 5 to 6; specific gravity, 4.5 to 5; color, iron black with a 

 submetallic luster and streak; opaque. Differs from magnetite, which 

 it somewhat resembles, by its crystalline form and by its influencing 

 but slightly the magnetic needle. 



Node of occurrence. Its common form is massive, or in thin plates 

 or laminse, or as small granules, sometimes disseminated through the 

 mass of rock or loose in the sand. In microscopic forms it is a com- 

 mon constituent of eruptive rocks, both acid and basic. Not infre- 

 quently it occurs in large masses, closely resembling magnetic iron 

 ore (Specimen No. 63861, U. S.N.M.). In the parish of St. Urbian, Bay 

 St. Paul, Province of Quebec, Canada, is such a bed, stated to be 90 

 feet in thickness and to have been traced, with some interruptions, for 

 a mile. The bed is in anorthite feldspar rock of Laurentian age. The 

 ore is quite pure, and carries some 48.6 per cent titanic acid. At 

 Kragero, in Norway, the mineral occurs in the form of veins in diorite. 

 In Virginia it is found in granular masses, containing apatite. (See 

 Phosphate Series.) 



Uses. The mineral has as yet proved of little economic importance. 

 It is stated that the presence of titanium has an important bearing 

 upon the qualities of iron and steel, but as such it is beyond the scope 

 of this work. As long ago as 1846 an attempt was made to use a 

 ferrocyanide of titanium as a green paint in place of the poisonous 

 arsenical greens. Later (1861) other patents were granted in England 

 for titanium pigments. A deep-blue enamel, resembling the smalt 

 prepared with the oxide of cobalt, has also been prepared from it, 

 but as yet the mineral, though abundant and cheap, has practically no 

 economic use. 



8. RUTILE. 



Composition and general properties. This, like ilmenite, is a titanium 

 oxide, having the formula TiO 2 , = oxygen, 40 per cent, and titanium, 

 60 per cent. The hardness is 6 to 6.5; specific gravity, 4.18 to 4.25; 



