GNEISS. 265 



The following are those of most usual oc- 

 currence: 



Epidote. Carbonat of lime. 



Garnet. Zircon. 



Actinolite. Tourmalin. 



Quartz. Melanite. 



Felspar. Idocrase. 



Hornblende. Oxydulous iron. 



Fluor spar. Molybdena. 



Garnet and Epidote are sometimes so abun- 

 dant as to modify the character of the rock. The 

 quartz and felspar present various colours and 

 characters ; more so than in any other rock in 

 which they occur. 



Many other minerals have been occasionally 

 described as found in gneiss, but the true reposi- 

 tories of these appear to be the granite veins : or, 

 at least, sufficient care has not been taken so to 

 distinguish between the two cases, as to admit of 

 their being here enumerated. The preceding 

 list includes those which have been observed in 

 the gneiss itself. 



It does not appear, that the geological rela- 

 tions of the Topaz rock of Werner have been 



