146 PHYSIOGRAPHY. 



Copperas Copper Mica. 



Compound Varieties. Slalactitic, botryoidal, reniform : 

 composition columnar ; if the particles become very thin, 

 the lustre approaches to pearly. Massive : composition 

 granular. Pulverulent. 



1. Before the blow-pipe it becomes magnetic, arid colors glass of bo- 

 rax, green. It is easily soluble in water, and the solution becomes black 

 on being mixed with tincture of galls. If exposed to the open air, it 

 soon becomes covered with a yellow powder, which is persulphate of 

 iron. 



2. Analysis. 



By BERZELIUS. 



Oxide of iron .... 25-7 



Sulphuric acid .... 28-9 



Water .... 45-4 



3. In most cases, the present species is produced by the decompositions 

 of other minerals, particularly of Iron Pyrites and White Iron Pyrites; 

 and it is therefore commonly found in such places, in which artificial 

 heaps, constructed for that purpose, mines, or other circumstances 

 brought about by art, have given occasion to its formation. It is also 

 found dissolved in the waters of several mines. 



4. It occurs in the Rammelsberg near Goslar in the Ilartz, at Schwar- 

 zenberg in Saxony, in several mines in Schemnitz in Hungary ; also in 

 Sweden, in Spain, in different coal mines in England ; at Hurlet in Ren- 

 frewshire in Scotland. In the United States, numerous localities of 

 Copperas have been discovered, especially in New England, in which 

 section of the country it exists in the form of crusts upon the surfaces of 

 those mica-slate rocks, which happen to abound ia Iron Pyrites. 



5. Both the natural and the aitificial Copperas are used in dyeing, in 

 making ink and Prussian blue, and also for producing sulphuric acid; 

 the residue from the distillation being red oxide of iron, is employed as a 

 color, and for a polishing substance. 



COPPER MICA. Rhombohedral Euchlore- 

 Mica. MOHS. 



Primary form. Rhomboid. P on P = 69 30'. 



