82 THE PROSPECTOR'S HANDBOOK. 



The ochre, which frequently accompanies it, is yellowish. 

 The phosphate, yellow or greenish. 



ZINC. 



Minerals to be tested for zinc should be treated along 

 with carbonate of soda on charcoal, before the blowpipe. 

 The presence of the metal is known by the incrustation on 

 the charcoal (very luminous when strongly heated) which is 

 when hot, yellow ; when cold, white. If the incrustation 

 be moistened with nitrate of cobalt and heated, a fine green 

 colour results. Before B.F., the metal is not obtained. 



Calamine (carbonate of zinc}. 



This is the most important ore. Massive, stalactitic, and 

 not quite transparent. 



Colour when pure, pearly white ; but owing to pre- 

 sence of iron oxide, &c., generally brownish, some- 

 times green. 



Streak whitish . 



Lustre pearly or glassy. 



Structure brittle . 



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



When pure, contains 52 per cent, of zinc ; the rest, 

 oxide of iron, carbonate of line, and magnesia, &c. 



Infusible alone before the blowpipe. Like other carbo- 

 nates, effervesces in acid. Sometimes looks like calc spar. 



Zinc Blende (sulphide of zinc, commonly called Black Jack). 



Massive and fibrous ; crystallizes in octahedrons and 

 dodecahedrons. 



Colour when pure, yellow and transparent, but more 

 usually, brownish red, garnet red, or blackish and 

 translucent. 



Streak white to reddish brown. 



Lustre waxy. 



H. 3-5 to 4 ; S.G. 4. 



Some specimens become electric. 



Contains nearly 67 per cent, zinc : the rest sulphur, &c. 



