286 PHYSIOGRAPHY. 



Iron Pyrites. 



duce, in the black limestone quarry of the former place, and in the wa- 

 ter limerock of the latter, the handsomest crystals we have yet discov- 

 ered. The secondary limestones in the vicinity of Marietta, (Ohio,) af- 

 ford interesting crystals. 



5. Iron-Pyrites is roasted for extracting sulphur ; after which it is ex- 

 posed to the oxidating influence of the air for the production of sulphate 

 of iron. 



IRON SINTER. 



Reniform, stalactitic . . . massive. Composition impalpable. 

 Fracture conchoidal. 



Lustre vitreous. Color yellowish-, reddish-, blackish-brown. 

 Transparent . . . translucent on the edges. 



Not very brittle. Soft. Sp. gr. = 2*40. 



1. Before the blow-pipe, it intumesces, and some varieties emit a 

 strong arsenical odor, during which they are partly volatilized. 

 2. Analysis. 



By KLAPROTH. By KERSTEJV, BySxROMEYEiu 



fr. Freiberg. 



Oxide of iron - 67-00 - - 40-45 - - 33.46 



Arsenic acid - 0-00 - - 30-25 - - 26-06 



Sulphuric acid - 8-00 - 0-00 - - 10-75 



Protoxide of manganese 0-00 - - 0-00 - , 0-59 



Water - 25-00 - - 28-50 - - 28-48 



3. It is found in several old mines, as Freiberg and Schneeberg in 

 Saxony, and in Upper Silesia. 



ISERINE. 



In small rounded grains. 



Cleavage scarcely distinguishable. Fracture conchoidal. 



Lustre semi-metallic. Color black. Streak black. 



Hardness = 5-5. Sp. gr. = 4-68 . . . 4-78. 



1. Before the blow-pipe, alone, on charcoal, it is unalterable. With 

 the fluxes, it acts in general like Magnetic-Iron ; but with the salt of 

 phosphorus, it presents in the reduction flame a bluish-red color. 



2. Analysis. 

 By ROSE, - By KLAPROTH, By BERTHIER, 



fr. Norway, fr. Iserweise. fr. Cornwall. fr. Brazil. 



Titanic acid - 43-73 - 50-12 - 45-25 - 43-5 



Peroxide of iron - 42-70 > ^Q.OQ i nn KA n 



Protoxide of iron- 13-575 ' 49 88 ' 51 ' ' 54>0 



Oxide of manganese 00 - 0-00 - 0-25 - 0-0 



Silica - 000 - 0-00 - 3-50 2-50 



