1858.] 



HAUGHTON — GRANITES OF IRELAND. 



303 



No. 3. Granite from Goragh Wood station, north of Newry, medium-grained, 

 composed of quartz, white felspar and black mica. 



No. 4. Granite, of gneissose structure, from the cutting south of Goragh Wood 

 Station, medium- grained, composed of quartz, red felspar, and green mica, 

 arranged in a flaky gneissose manner. 



Table IV. 



— Analyses of Soda-Granites. 





1. 



2. 



3. 



4. 





64-60 

 14-64 

 6-04 

 8-16 

 2-80 

 3-15 

 4-02 



1-13 



74-20 

 10-84 



1-88 



2-84 



Trace 



3-12 



4-77 



0-83 



62-08 

 15-92 

 7-72 

 5-52 

 2-16 

 2-19 

 334 



0-89 



66-56 

 13-52 

 6-76 

 1-20 

 1-32 

 2-73 

 3-75 

 0-18 

 2-19 





Peroxide of iron... 









Protoxide of iron . 

 Loss by ignition... 



Totals 



99-54 



98-48 



99-82 



98-21 





The elvan-dike (No. 2) differs from the other three granites in 

 the large per-centage of quartz, which is a general characteristic of 

 elvans and felstones, but agrees with them in the relative proportions 

 of the two alkalies. 



Reserving the elvan-granite for a separate discussion, I shall now 

 tabulate the atomic quotients of the other granites, which appear to 

 belong to the same family of rocks. 



Table V. — Atomic Quotients of Soda-Granites. 





1. 



3. 



4. 





1-435 

 0-281 

 0-075 

 0-011 

 0-140 

 0-067 

 0-130 



1-375 

 0-306 

 0-096 

 0019 

 0-108 

 0-046 

 0-108 



1-479 

 0-260 

 0-084 

 0-004 

 0-066 

 0-058 

 0-121 

 0005 





Peroxide of iron... 







Soda 



Protoxide of iron . 



Adding together the silica, peroxides, and protoxides from the 

 preceding Table, I find — 



Table VI. — Atomic Quotients of Silica, Peroxides, and Protoxides 



in Soda-Granites. 





1. 



3. 



4. 



Average. 





1-435 

 0-356 

 0-348 



1-375 

 0-402 

 0281 



1-479 

 0-344 

 0-254 



1-429 

 0-367 

 0-294 



Peroxides ... 

 Protoxides . . . 



It is evident from a comparison of Tables I., II., III., with Tables 



