NICKEL ORES. 73 



Crystallization hexagonal. 



Colour copper red (greyish or blackish when tar- 

 nished). 

 Streak paler. 

 Lustre metallic. 

 Structure brittle. 

 H. 5 to 5-5 ; S.G. 7'3 to 7'7. 

 Composition 35 to 45 per cent, of nickel, the rest 



chiefly arsenic. 



Often resembles native copper, but is harder. Soluble in 

 aqua regia, and forms a green solution which becomes a 

 violet blue by the addition of ammonia. 



"White Nickel (nickel glance). 



Crystallization cubical. 



Colour silver white or steel grey. 



Streak greyish black. 



Lustre metallic. 



Structure brittle. 



H. 5-5 to 6 ; S.G. 6.4 to 6-7. 

 Composition 25 to 30 per cent, nickel, the rest arsenic 



Soluble in aqua regia. 



Emerald Nickel (a carbonate of nickel). 



Is of a bright green colour, and contains 2S'6 per cent, 

 of water. 



In addition to the above may be mentioned the prolific 

 hydrated silicate of nickel found in New Caledonia. 



Colour green, light or dark. 

 Streak tight green. 

 S.G. 2-2 to 2-86 ; H. 2-5. 



Gives off water when heated. Fuses in borax before 

 B.F., and gives the ordinary nickel bead. Is a silicate of 

 nickel and magnesia, with iron, &c. Good specimens yield 

 12 per cent, nickel. Is found in lodes and pockets in ser- 

 pentine rock. Matrix, cellular silica. Sometimes in a 

 lode, the nickel is replaced by cobalt. Sometimes associated 

 with chrome iron. 



Excepting the New Caledonia ore, the principal ore is 



