178 ME. E. K. C0WPEK KEED ON THE GEOLOGY OE [May 1895, 



by F. H. Hatch 1 show many points of resemblance with those from 

 the Fishguard area, and the author suggests that the striated 

 felspars may belong to Rosenbusch's anorthoclase series, 2 analogous 

 to the soda-orthoclase or soda-mierocline described by Forstner in 

 the liparites of Pantelleria, 3 by Brogger in the augite-syenite of 

 Southern Norway, 4 and by Miers and Fletcher from Kilimanjaro. 5 



The almost entire absence of lime in the Irish and Fishguard 

 examples and of microperthite, which Lossen states is generally 

 present, are important points of difference from the foreign kerato- 

 phyres. The analyses of some of the British and foreign rocks are 

 here given for comparison : — 



I. II. III. IV. V. VI. 



SiO„ 71-12 70-97 73-6 75-6 68-01 7206 



A1 2 3 14-58 13-84 13-8 12-8 1748 14-87 



F e ;0 3 1-69 321 05 ... 041 1-33 



MgO 0-15 0-20 0-7 0-4 0-46 1-26 



OaO 1-50 1-26 0-6 0"1 trace trace 



Na 2 326 627 3-2 30 577 411 



K 2 601 1-57 4-3 5-6 7-08 590 



H„0 0-95 0-74 ... ... 0-73 0-26 



Ti0 2 (ZrO 2 ) 0-25 



FeO 0-78 2-4 1-9 



MnO 0-12 



P 2 5 0-08 T , T , 



CO, 0-79. L °f son l 0-6. Lo !. son l 0-5 



2 ignition. J ignition. J 



99-26 100-08 99-7 99-9 99-94 99-79 



Specific gravity 2-65S 2-626 2-60 270 



I. Liparite from the Island of Ponza (Kalkowsky). 

 II. Quart z-keratophyre from the Harz (Jacobs). d 



III. Potash-soda felsite, Co. Wicklow (Hatch). 



IV. Do. do. do. 



V. Potash-soda felsite [76], Goodwick, Pembrokeshire (Tadman). 

 VI. Potash-soda felsite [203], Cam Gelli, near Goodwick (Tadman). 



An analysis of the dark olive-green ' re-cemented lava-flow ' 

 (mentioned on p. 176) gives the following result (C) : — 



C. D. 



SiO„ 72-33 76-00 



Al 2 6 3 13-78 15-01 



Fe,0 3 4-02 0-34 



K 2 5-05 5-28 



Na 2 1-64 1-54 



MgO 1-59 0-95 



CaO trace trace 



K 2 1-34 0-74 



99-75 99-86 



Specific gravity... 2'65 2-60 



1 Explan. Mem. Sheets 138, 139, App. P. p. 49, Geol. Surv. Ireland (1888) ; 

 Geol. Mag. 1889, pp. 70, 288, 545 ; Brit. Assoc. Eep. (Newcastle, 1889) p. 568. 



2 'Mikroskop. Physiogr.' 2nd ed. vol. i. (1885) p. 550. 



3 Zeitschr. f. Krystallogr. vol. viii. (1884) p. 125. 



4 ' Die silur. Etagen 2 & 3/ Christiania, 1882, p. 261. 



5 Mineral. Mag. vol. vii. 1887) p. 131. 



