REPORT OF THE DIRECTOR I917 183 



The molecular proportions of ga are shown below, the second 



column being based upon A1 2 3 as i and the third on (MgFe)O 

 as 3. 



Si0 2 .422 2.26 1.86 



AI2O3 .186 1. 00 .83 



FeO 



MgO / - 673 3 " 6 ° 3 °° 



H 2 r .668 3.60 3.00 



For 10a the corresponding figures are: 



S1O2 .409 1.86 2.097 



AI2O3 .219 1. 00 1. 128 



M g o:.'::::::::::::::::::::::::::::::::::} ■& 2 - 66 3.™ 



H2O .610 2.77 3.12 



The divergence from theoretical quantities is even greater here 

 than in the preceding cases, but a rough approximation to the same 

 simple ratios may be seen. 



These specimens of green and red oolite, while closely related to 

 the typical oolitic ore, differ from it in certain respects, being, in a 

 sense, intermediate between it and the gray oolite. Therefore, to 

 carry the series farther, and to its normal limit, analyses n and 12 

 were made, the first representing the spherules of the ordinary oolitic 

 ore (plate 5, figure 1) and the second representing the irregular 

 grains of the so-called fossil ore, both collected from the type deposits 

 at Clinton, N. Y. 



The spherules and grains were separated from the fine clastic 

 material and cement in order to secure as large an amount as 

 possible of the ferrous silicate, which is largely confined to the 

 former. 



The low P2O5 shown in these analyses is, doubtless, due to the 

 elimination of phosphatic lingula fragments during the separation 

 of spherules and grains from cement, while the same operation has 

 increased the amount of insoluble silica in no. 11 because this occurs, 

 largely, as rounded quartz grains, forming the cores of spherules. 



Of this sample, 73.66 per cent is hematite, 11. 61 per cent is con- 

 sidered ferrous silicate, 11. 91 per cent quartz, the remaining 3 per 

 cent being calcite, pyrite etc. 



This composition is in sharp contrast with that of the gray oolite, 

 numbers 1 and 2, with only 1.70 per cent and 0.83 per cent, respec- 

 tively, of hematite, 38.84 per cent and 44.41 per cent of ferrous sili- 

 cate and 24.21 per cent and 28.81 per cent of quartz. 



