On the Paragenetic Relations of Minerals. 145 



At other places the large number of pyritic minerals are 

 wanting, and are replaced as at Prizebram by spathic iron. 

 Here the "hut" may originate from the alteration of spathic 

 iron. In the neighbourhood of Prizebram, the lodes of iron 

 ore are leased to private individuals only to a certain depth, 

 because the more valuable pyritic ores occur below that depth, 

 and these are worked by the government. 



At other places, the various iron and manganese ores of 

 the " eisenen Hut*' are certainly more recent than other 

 minerals on the same lodes, and present a genetic character 

 distinct from them. 



Although it is true that most lodes of iron ore continue as 

 such to all accessible depths, still some of the deposits of 

 ferruginous minerals ought not to be altogether overlooked 

 or disregarded, especially when they occur in true lode dis- 

 tricts, for it is probable that in many instances such a depo- 

 sit may be the iron hat of a lode. 



V. Cobalt and Nickel formations in general. — Not only 

 are minerals containing these elements very generally as- 

 sociated together, but in almost every mineral which con- 

 tains one of them as an essential constituent, at least traces 

 of the other enter its composition. Arsenic enters more 

 largely than sulphur into the composition of the more fre- 

 quent of these minerals, so that it might be termed the co- 

 balt, nickel, and arsenic formation. Metallic arsenic has 

 even been found. Bismuth minerals are in some localities 

 such constant associates that they might be regarded as es- 

 sential, while in others they are altogether absent. How- 

 ever, they occur unaccompanied by cobalt and nickel minerals, 

 although the arsenik-kies of Altenburg contains nickel, and 

 bismuth glance is a frequent associate of copper pyrites. 



Copper pyrites, and sometimes its ordinary products of 

 composition, especially malachite, kupperfecherz, accompany 

 the minerals of this formation. Linneite is never without cop- 

 per pyrites, although large masses of it have not been found. 

 Arsenical iron pyrites occurs, though not largely. The uran- 

 pecherz occurs sporadically, especially in one group of this 

 formation. 



The principal lode substances (gangarten) are spathic iron 



VOL. LVI. NO. CXI. — JANUARY 1854. K 



