Vol. 59.] GRANITE AND GREISEN OF CLIGGA HEAD. 159 



merely wished to state, from a study of certain slides and observations 

 in the field, that as a general rule the tourmaline in the killas 

 bordering the lodes and granite was brown, while that in the quartz 

 of the lodes was blue. Although he had not found it yet, he would 

 expect some blue tourmaline in the killas, on account of the abund- 

 ance of felspathic grits ; and, on the other hand, he admitted that 

 there were exceptions to the blue tourmaline in the lodes. The 

 Author's object in entering into this question at length was to 

 strengthen his contention that none of the brown tourmaline in the 

 Cligga-Head greisen was derived from the felspar, and that therein 

 the rock differed from luxullianite and trowlesworthite. In con- 

 clusion, he expressed his gratitude for the cordial manner in which 

 his paper had been received. 



