MINERALOGY OF THE OCHILS. 



19 



rock, which Mr Jameson calls Sienitic Greenstone. 

 It is occasionally porphyritic, containing fine and 

 indistinct crystals of rutilite. 



X. Clayst07ie-Porphyry. 



On the south side of the Abernethy hills, a bed 

 of flesh- red claystone porphyry, with crystals of 

 glassy felspar, is above the clinkstone, and some 

 varieties of greenstone, but its relations are wholly 

 undefined. 



XI. Felspar -Porphyry 



Forms the caps of the highest hills which lie be- 

 tween Dunning and Dunblane. It is a compact 

 fiesh-red felspar, containing crystals of white calca - 

 reous * spar. In the course of the streamlet which 

 runs past Castle Campbell, it alternates with green- 

 stone. It occurs in decomposed fragments on the 

 summits of Craiginnan, King's Seat, Eencleugh, 

 and Dalmyatt. These decomposed fragments have 

 a vesicular appearance, from a very obvious cause, 

 (the rapid decomposition of the included crystals). 

 This appearance would no doubt be ascribed to 



b2 



• This appears to be intimately connected with the sienitic 

 greenstone. Some beautiful masses of this rock are to be seen 

 higher than the greenstone, at Craig Rossic;, near to Dunning, 



