36 MINERALOGY. 



56. Bulphuret of Mercury. This is more abundant than 

 any of the other ores of mercury, and most of this metal 

 is obtained from it. It is called both cinnabar and ver- 

 milion. The latter is its name as sold in the shops. It 

 is used as a pigment, and is the coloring matter in red 

 sealing-wax. The principal mines of this ore are in Aus- 

 tria, Spain, Peru, and Upper California. 



5V. Sulphuret of Zinc. This mineral, commonly called 

 blende, the Black Jack of miners, appears in octahe- 

 drons, dodecahedrons, and forms that are secondary to 

 these. It has a waxy lustre, and when a cleavage face 

 is made the lustre is brilliant. It is very apt to be found 

 in company with lead ores, and it abounds in the lead 

 mines of Missouri and Wisconsin. 



58. The Three Vitriols. The green vitriol (sulphate 

 of iron), the blue (sulphate of copper), and the white 

 (sulphate of zinc), are all familiar to you. They exist in 

 nature in company with the sulphurets of the same met- 

 als, from which they are really produced. A sulphate 

 differs from a sulphuret in having oxygen in it, as you 

 learned in Part II. Now if a sulphuret, of iron for ex- 

 ample, be exposed to the air in a moist state, it is decom- 

 posed, and the sulphur and the iron, absorbing oxygen 

 from the air, become, the one sulphuric acid and the oth- 

 er oxyd of iron, and these two uniting form sulphate of 

 iron. So also sulphate of copper is formed from sulphu- 

 ret of copper, and sulphate of zinc from sulphuret of zinc. 



, Green vitriol, or copperas, is largely used in dyeing 

 and tanning, because, in connection with an ingredient in 

 nut-galls and many kinds of bark, it gives a black color. 

 Common ink is essentially a combination of copperas 

 with this ingredient. 



59. Sulphate of Lead. This is usually in company with 

 galena, and is the result of its decomposition, after the 

 manner indicated in speaking of the vitriols. Its color is 

 white, or light gray, or green. Its crystals are some- 

 times splendid. 



