264 



THE CEYSTAL FALLS lEON-BEAEING DISTEIGT. 



Taulu II. — Percentages of chief oxides reduced to 100. 



SiO.... 

 TiO. . 

 AI.O., 

 Fe.O., 

 FeO.. 

 CaO-- 

 MgO . 

 K,0.. 

 Na,0 . 



60.36 

 .75 



16.83 

 2.17 

 4.57 

 4.04 

 3.85 

 4.21 

 3.21 



50.52 



.80 



20.25 



6.41 



.50 



11.50 



7.15 



.62 



2.25 



49.64 

 1.03 



18.79 

 1.30 

 6.28 

 9.67 



11.16 



.75 



1.38 



47.33 



' 1.02 



6.22 



3.60 



8.78 



9.25 



22.11 



.78 



.96 



Table III. — Atomic proportions of metals. 



The analyses show that all of the rocks contain a moderately large 

 amount of water. Nevertheless, they are sufficiently well preserved to 

 warrant a discussion of their analyses for classification pui-poses. This is 

 especially true of No. 4, which is remarkably fresh for so basic a rock. 



The chief rock-making oxides in the above analyses appear in Table 

 II reduced to 100. The molecular proportion of these oxides was then 

 obtained. From these data the atomic proportions of the metals were 

 derived, and are given in Table III. These calculations were kindly made 

 for me by Mr. V. H. Bassett, assistant in the chemical laboratory of the 

 University of Wisconsin. 



If we examine Table II we see that, in passing from the more acid to 

 the basic end of the series, in coiTespondence with this decrease in silica 

 the alumina increases rapidly, then decreases until it reaches the extreme 

 basic rock, when it di-ops suddenly to 6.22 per cent. The analyses also 

 show an increase in iron, which is best brought out in Table III. The 

 alkalies decrease with diminishing silica, whereas the MgO, which for 

 rocks of this chai'acter is very characteristic, shows a decided increase. 

 Within the gabbro-norite-peridotite series (Nos. 2, 3, and 4) the lime shows 



