360 



Scientific Geology. 



whole, my belief is that the iron is connected with the latter rock. 

 For the large deposits of this ore in other countries most frequently 

 occur in the older schistose rocks, and rarely in granite.* In Massa- 

 chusetts too, no mineral is so widely disseminated in talcose slate as 

 magnetic oxide of iron. 



A part of the Cumberland ore is beautifully porphyritic by the 

 presence of crystalline masses of white feldspar. In another portion 

 we find a mineral disseminated, which appears to be the ferro-silicate 

 of manganese. Imbedded noddles of what appears to be serpentine are 

 also found in the ore : and these substances probably do not a lit- 

 tle injury to the ore. For 1 was told it did not yield more than 25 or 

 30 per cent of iron. 



In the first part of my Report I have given a full account of the 

 native gold found in connection with this iron. Since that time it has 

 been ascertained that the common gangue of the gold is the hydrate 

 of iron : but whether enough of the metal exists in it to render it an 

 object to separate the gold, has not been determined. Usually quartz 

 exists in connection with the hydrate of iron. This is porous and 

 contains the hydrate, and exactly resembles the gangue in which gold 

 has been found in the Southern States. For comparison I have placed 

 specimens from Somerset and from Virginia in the collection. 



This porous quartz and the hydrate of iron are very common 

 throughout the talcose slate of Hoosac Mountain ; and the iron re- 

 sults, if I mistake not, as already mentioned, from the decomposition 

 of the carbonate. Whether the hydrate at Somerset had such an ori- 

 gin, I have no means of ascertaining ; but if ever gold should be 

 found at other places in this formation, I predict it will occur in con- 

 nection with this hydrate of iron. 



Quartz and hydrate of iron then, appear to be the immediate ma- 

 trix of the gold of Somerset ; and talcose slate the rock in which the 

 quartz and iron are contained. It is rare that we can at once trace 

 this metal so satisfactorily to its original bed. But so far as can be 

 judged by specimens, we may expect that such will be found to. be the 

 situation of the gold in the Southern States. For those specimens 

 contain quartz, hydrate of iron, and talcose slate. (Nos. 848, 849, 850.) 



This geological situation of the Vermont gold corresponds re- 

 markably with its situation in other countries ; particularly in Brazil. 

 It is described as occurring there, disseminated in a rock, called by 



*Beudant's Mineralogie, vol. 1. p. 622. 



