Vol. 68.1 



PALEOZOIC EOCKS OF THE KILBEIDE PENINSULA. 



93 



I. 



II. 



III. 



I. TI. III. 



SiO., 54-20 55-38 56-50 



A1,0., 21-00 18-34 18-14 



FelO, 2-60 1-13 3-12 



FeO 4-32 5-86 2-86 



MnO trace 



CaO 3-80 3-25 3-38 



MgO 2-02 3-47 1-22 



K,0 0-42 0-22 1-60 



Na,0 6-58 7*12 5-28 



TiO, 2-60 0-90 0-85 



P^Og 004 trace 



CO., 1-57 2-00 5-11 



Water at 110°C 0-481 -..o^. 



Water (combined) 1-23 2-39/ ^ "^ 



Totals 100-38 100-.54 90-32 



Specific gravity = 2-68 2.73 



Lime-boston ite from Kilbride (analysed, by J. Weintraube). 



Lime-bostonite from St. David's (analysed by J. V. Elsden). 



Lime-bostonite from Msena, W. C. Brogger, Q,. J. G. S. vol. 1 (1894) p. 



Calculating the percentages of albite and anorthite from the soda 

 and lime, Dr. Elsden gets for his felspar : — 



Albite 60-26 



Anortbite 36-12, 



which amounts to 76-38 per cent, of a plagioclase between Ab^An^ 

 and Ab.,An^. 



Por the Kilbride rock we get : — 



Albite 5.5-61 



Anorthite 18-86, 



which amounts to 74*47 per cent, of a plagioclase corresponding to 

 the formula AbgAn^. 



If we calculate the amounts of silica and alumina needed to 

 form felspars with the lime and alkalies, we arrive at the following- 

 result : — 



SiO., 



Al.,0., 



Ab. 



An. 



K,0 . AW, . 



" 6sio:. 



Total. 



Observed. 



38-21 



10-32 

 658 



8-14 

 6-92 



3-8 



1-61 

 0-46 



0-42 



49-48 



18-20 



6-58 



0-42 



3-8 



54-20 



21-00 



6-.58 



0-42 



3-8 



Na'^d .... 



K^O 



CaO 





It will be observed that the silica and alumina needed for 

 the above suppositions are less than the observed amounts. The 

 excess of these oxides is no doubt due to some of the silica and 



