22 



Proceedings of the Royal Irish Academy. 



light, not only the hornblendic and quartz granules, but also abundant 

 magnetite and Titanic iron.^ 



A sample of the rock was submitted for analysis to Mr. S. 

 Templeton, As. E..C.S. Dub., and F.G.S. of Belfast, and he reported 

 the composition thereof as follows : — 



Si02, 



50-16 \ 



A1203, 



14-00 



FeO, 



14-042 



MgO, 



7-62 



CaO, 



. ' 9-60 



NaaO, 



3-97 



H2O, 



0-39 j 



99-695. 



This may be compared with the following analysis : — 







[Sp. 



Gravity = 3-11 



-] 







1.3 





II.* 



SiOs, . 



48-90 





49-78 



AI2O3, 







16-02 





13-13 



FesOs, 







12-52 





4-35 



FeO, 







1-12 





11-71 



MnO, 







0-04 





— 



CaO, 







8-22 





8-92 



MgO, 







6-24 





5-40 



K2O, 







1-17 





1-05 



NaaO, . 







3-87 





2-39 



Ti02, 







0-26 





2-22 



Loss on ignition, 



1-66 



H2O, 



1-14 











CO2, 



0-10 



100-2 



100-19 



Teal says, p. 197 : — 



"■ Eiglilands of Scotland. — Basic, igneous rocks, essentially com- 

 posed of plagioclase and pyroxene, are found associated with the 

 gneisses and schists of the region. They have not as yet received 



1 See notice of it by Henry J. Seymour, b.a., in the Irish Naturalist, 1896, 

 p. 137. 



^ A small fraction of the iron was found to exist as Fe203. 



3 From Zirkel's Le.hrhuch der Petrographie (vol. ii. 1894, p. 485) of aquartzose, 

 diorite from Swartzenberg (Vosges). 



* Bulk analysis of a hornblende schist taken from Teale's British Petrography, 

 1888, p. 200. 



