Yol. 65.] PL ANT-CON rAINING NODULES FROM: JAPAN. 201 



fundamental difference in the specimens, though the first has a 

 rather larger proportion of carbonates and the second a larger pro- 

 portion of silica. 



The nodules consist primarily of calcium carbonate and silica, 

 as would be expected from the nature of the crystals in the coarse 

 matrix. 



The following analyses are carried out in rather more detail, but 

 show a similarity to the foregoing in the main feature, namely, 

 that the nodules consist primarily of carbonates and silicates. The 

 presence of aluminium is to be noted (aluminium silicate was 

 probably classed as silica by the first analyst) in these nodules, 

 as its practical absence from the ' coal-balls ' is a striking feature 

 of their composition. 



Analyses ey Mr. Barnes. Japanese Nodules. 



Many fragments from a 

 Typical number of nodules, to give 



nodule. a fair sample of the whole. 



Calcium carbonate, CaCO, 59391 ] rn ,, nQ 58-256 j ,-n.,^ 



Magnesium carbonate, MgC0 3 ... 1-018 | 0U4UJ 0924 J 0J 10U 



Iron carbonate, FeC0 3 1-739 2456 



Insoluble inorganic substances, 



mainly aluminium silicate 32'256 30'744 



Manganese carbonate, MnC0 3 ... 0896 2 4 279 



Calcium phosphate, Ca 3 P 8 0-811 1-600 



Iron pyrites, FeS„ ........ 0743 0-483 



Carbon (organic),"C 1-545 0993 



Aluminium hydrate, Al 2 H O 3 ... 1-497 2-522 



Totals 99-896 99-957 



For the sake of comparison, analyses are tabulated of a ' coal-ball ' 

 and of a ' roof-nodule ' : — 



Analyses by Mr, Barnes. (From Stopes & Watson, op. cit. pp. 193 & 197.) 



' Coal-ball.' ' Hoof-nodule! 



Calcium carbonate, CaC0 3 52-378 1 Q9 oro 847001 Sf , onn 



Magnesium carbonate, MgC0 3 ... 39'884 f ^ ^ 1-600 / 8D oW 



Iron carbonate, FeC0 3 2973 2"448 



Aluminium silicate (clay) 0O00 6*447 



Manganese carbonate, MnC0 3 ... 1-167 1-808 



Calcium phosphate, Ca 3 P 8 trace trace 



Iron pyrites, FeS 2 .". . . 0783 1 -280 



Iron oxide, Fe„0 3 0113 



Carbon (organic), C 2'281 1473 



Aluminium oxide, Al 03 trace 0'216 



Water, H 2 '. 0-283 0-000 



Totals 99-862 99-972 



