and Associated Rocks. 



459 



much as 14 per cent. The distribution, of the largest augites is also 

 irregular, while it is curious that the very large crystals are often 

 extraordinarily rich in inclusions. In the large quarry there are 

 found several rocks which appear even-grained in the hand-specimen 

 and some of which have pink felspar. In thin section, these are 

 decidedly porphyritic, but the augite-phenocrysts are much smaller 

 than in the rocks described above. The pink colour of the felspars 

 is due to the fact that the latter are much ' analcitized ', 1 being 

 sometimes totally replaced by a dusty aggregate of analcite and other 

 zeolites, although the interstitial analcite is often limpid and quite 

 unaltered. In the neighbourhood of these rocks small clots, poor in 

 ferromagnesian minerals but with abundant felspar and analcite, often 

 occur. 



100-17 100-21 100-16 100-40 100-07 



99-91 



1. Essexite, Craighead, analyst A. Scott. 



2. Essexite, Lennoxtown, analyst W. Pollard. 2 



3. Essexite, Brandberget, analyst L. Schmelk. 3 



4. Essexite, Mt. Royal, Montreal, analyst B. J. Harrington. 4 



5. Theralite, Barshaw, analyst E. G. Badley. 5 



6. Augite (with inclusions), Craighead, analyst A. Scott. fi 



A sample of the fresh rock from one of the exposures on the 

 hillside has been analysed and the results are given in column 1, 

 table ii, several other analyses being included for comparison. The 

 composition of the Craighead rock is very similar to that of the 

 Lennoxtown essexite, and both resemble closely the Brandberget type. 

 It was on account of this chemical resemblance that Bailey 7 classed 

 the two former rocks as essexites. The name essexite was given 



1 Cf. J. S. Flett in Geology of Edinburgh (Mem. Geol. Surv.), 1910, p. 295. 



2 Summary of Progress of Geological Survey for 1907, 1908, p. 55 ; E. B. 

 Bailey, loe. cit., p. 130. 



3 W. C. Brogger, loc. cit., p. 19. 



4 P. D. Adams, Geological Congress, Canada, 1913, Guide-book No. 3, p. 39. 



5 E. B. Bailey, loc. cit., p. 134. 



6 Another analysis of more impure material is given by G. W. Tyrrell, 

 Geol. Mag. [6], II, p. 363, 1915. 



7 Loc. cit. 



