USEFUL METALS 237 



T\\.> possible sources of the ores are suggested. (1) The metals 

 may have I .rm brought up from great depths by these waters. 

 (2). The nu-tals may havr I.een l.-aehed out of the disturbed 

 ami folded Kewatin scries of terranes. The arsenides appear to 

 have li.'fu I he first minerals depo>ited, after which the veins suf- 

 fer. ,1 some disturbance which resulted in the formation of cracks 

 and minute fissures favoring the deposition of the silver at a 

 later time. A proof that disturbance preceded the deposition 

 lies in the fact that the silver cuts the arsenides and that the 

 undisturbed veins are non-argentiferous. The veins are small, 

 varying from 1 in. to 1 ft. or more in thickness. Some of 

 them are of remarkable richness. A single sample from thedow- 

 ganda camp assayed by E. E. Burlingame & Co. of Denver, 

 Colorado gave 27,066 oz. of silver per ton of ore. 



Geological Horizon. The commercial deposits of cobaltif- 

 erous minerals are found in the older geological formations from 

 the pre-Cambrian to the Ordovician. 



Method of Extracting. The ores are roasted, smelted into a 

 matte, and subsequently refined by electrolysis. 



Uses of Cobalt. Metallic cobalt finds little application in the 

 arts and industries. Cobalt steel has a high elastic limit and 

 tensile strength but it is far more costly to manufacture than man- 

 ganese or nickel steel and therefore does not possess so wide an 

 industrial application. 



Cobalt is extensively used as a pigment in the manufacture of 

 glass and pottery. The beautiful blue color known as smalt 

 blue is imparted to the glass by the oxide of cobalt. Zaffre, the 

 roasted cobalt ore, cobalt oxide, arsenide, phosphate and sulphate 

 are used in the coloring of glass and the painting of porcelain. 

 Sympathetic inks are made of cobalt acetate and cobalt nitrate. 

 These inks are colored when heated and colorless when cold. This 

 is said to be due to a change in the color of the salts upon the 

 absorption of water. Cobalt and potassium nitrate are used as 

 an oil and water pigment for painting on glass and porcelain. 

 Cobalt nitrate is used in medicine. The salts of cobalt are an 

 antidote for the deadly prussic acid. The nitrate of cobalt is also 

 used in chemical mineralogy in the detection of aluminum, tin, 

 zinc and magnesium. Cobalt is also used in storage batteri. - 

 but it is expensive for that purpose. Cobalt is used in the manu- 

 facture of gold and silver ornaments. 



The banner domestic production including cobalt oxide in 



