MINERALOGICAL QUERIES. 



11J 



greenstone, occurs in the grey-wacke and grey- 

 wacke slate of these districts. 



20. Does the granite of Aberdeen and Peter- 

 head, belong to the oldest or to the newest 

 granite formation ? 



a i. Is the granular quartz of the islands of Isla 

 and Jura subordinate to mica-slate, or does it 

 constitute a distinct formation ? 



In my Outline of the Mineralogy of the Scottish 

 Isles, this rock is particularly described ; and I 

 have mentioned its alternation with a passage in- 

 to mica- slate, facts that render it probable that it 

 is subordinate to mica-slate. The opinion, how- 

 ever, cannot be considered as absolutely certain, 

 until the rocks of Isla and Jura be again examin- 

 ed. 



22. Are the Cullin mountains in the island of 

 Skye, composed of rocks belonging to the new- 

 est fioetz -trap or to the second porphyry for- 

 mations ? or do they contain both of these 

 formations ? 



23. What are the geognostic relations and 

 characters of the Scure Eigg, one of the 

 Hebrides ? 



The Scure Eigg, of which I have given an ac-* 

 count in my mmeralogical description of the island 



11 § 



