388 /. MORGAN CLEMENTS 



III. 



ATOMIC PROPORTIONS OF METALS. 



Si 



Ti - - - 



Al - - - 



Fe - - 



Ca - - - 



Mg - 



K ... 



Na - 



In Table II there is given the percentages of chief oxides 

 reduced to 100, and in Table III the atomic proportions of the 

 metals. 1 The analyses show that all of the rocks contain a mod- 

 erately large amount of water. Nevertheless, they are sufficiently 

 well preserved to warrant a discussion of their analyses for classi- 

 ficatory purposes. Indeed, No. 4 is remarkably fresh for so 

 basic a rock. With reference to analysis No. I, it may be stated 

 that the rock is, on the whole, one which it is somewhat difficult 

 to place definitely in the existing division of rock families. The 

 large amount of lime and relatively low percentage of alkalies 

 prevent placing the rock with the syenites, which possibly the 

 presence of the large amount of orthoclase might lead one to do 

 if the rock were studied with the microscope alone. On the 

 whole, it approaches close to the monzonites, according to their 

 chemical composition as given by Brogger. 2 From this it 

 differs, in that the lime, 3.92 per cent., is too low to bring the 

 rock within his limits, 4.52 to 10.12 per cent. However, if we 

 consider the total of the alkaline earths, 7.55 per cent., in this 

 rock, we find that it comes well within Brogger's range, 6.05 to 

 17.52 per cent., for a total of magnesia and lime. Moreover, the 

 alkali total, 7.19 per cent., is too high to warrant its classification 

 in the monzonite class as a representative of the type of the 

 biotite-monzonite. 



1 These tables were calculated for me by Mr. V. H. Bassett, assistant in chem- 

 istry in the University of Wisconsin. 



2 Op. cit., Part II, p. 51. 



