Origin of Granite. 



509 



In the 16th volume of the American Journal of Science, I have 

 given a very particular account of the single crystal of the oxide of 

 tin, which I found several years ago, at the well known locality of 

 several interesting minerals in the northwest part of Goshen. Its 

 form, if I did not mistake it, was an octahedron with a square base : 

 though the measurements of several of the angles did not coincide 

 with those given in the books. But as to its being genuine oxide of 

 tin, there can be no doubt: especially since the discovery in Europe 

 of this same substance in a specimen sent from Chesterfield, Mass. as 

 mentioned in Mohs Mineralogy.* 



. Mr. Nuttall suggests with a doubt, that the phosphate of manga- 

 nese exists in Sterling, in connection with spodumene. The same 

 mineral, whatever it be, is found in Goshen with the spodumene. 



Sulphuret of molybdenum has been found in granite in New 

 Bedford and Fitchburg. 



The only remaining mineral to be noticed in the granite of Mas- 

 sachusetts, is the columbite at Chesterfield. It was discovered at the 

 tourmaline locality by Mr. C. U. Shepard, in right rectangular prisms 

 with several modifications. The same gentleman found this rare 

 mineral in two places in Goshen, imbedded in spodumene. 



Theoretical Considerations. 



I have already expressed the decided opinion, that if an igneous 

 origin be assigned to the trap rocks, as is now done almost univer- 

 sally, a similar origin cannot be denied to granite. There is not in- 

 deed, so great a resemblance in appearance, between granite and re- 

 cent lavas, as between these and the trap rocks : nor does granite oc- 

 cur in columnar masses. But except in these two respects, the same 

 arguments which prove the igneous origin of the traps, equally apply 

 and sometimes I think with more force, in proof of the original ig- 

 neous fluidity and protrusion of granite. And if I mistake not, there 

 are one or two additional arguments in the case of granite. I shall 

 now briefly present these arguments as they apply to the granite of 

 Massachusetts. 



1. I infer the igneous origin of granite from the inclined position of 

 the older stratified rocks. The stratified and slaty structure of these 

 rocks is conclusive evidence that water was the medium of their orig- 

 inal deposition. But if deposited in water, their lamina? could not at 



• Vol.2 p 387. Edinburgh, 1825. 



