CHEMICAL ANALYSES 



Analyses of selected Specimens of Limonites 



481 



Fe 2 3 .. 

 MnO,. . 

 A1 2 3 .. 

 MgO .. 

 CaO . . . 



PA... 



Si0 2 . . . 

 Quartz. 

 H a O... 

 S 



Total 



1. 



OQ 



o 



g i 



CD 



PLH 



78.58 



.08 



.88 



.54 



.30 



.36 



4.25 



2.60 



12.41 



100.00 



Ph 5 



ClT.^ 



> 



Ph 



83.74 

 .31 

 .33 

 .34 



Tr. 



.14 



2.57 



.44 



12.13 



100.00 



M 



£ c8 



o-Q 



CD 

 ft 



78.57 

 .01 



1.21 

 .55 

 .62 

 .36 



7.65* 



11.16 



.028 



100.19 



Q 



rW 



3 * 



5. 



3 



Ph 



Ph 



83.13 

 .15 

 .74 

 .09 



Tr. 



.50 

 2.47 



12.92 



81.48 

 .07 

 .49 



Tr. 



Tr. 

 .08 



3.98 



13.00 



100.00 i 100.00 



S £ 

 o o 



2 ^ 5 



3 n S 

 O 2,Q 



5 ft^ 



82.00 

 Tr. 

 1.94 



.17 

 Tr. 



.37 

 2.98 



.44 

 12.10 



100.00 



p 5 



,_Q O 



^jj CD 



O o 



68.26 

 .19 

 .28 

 .08 

 .07 

 .96 



16.13* 



12.24 

 ,011 



98.22 



CJ CD 



O co 



CD >-) 



CM 5 



O °8 



=8 g 



S CD 



> £ 



62.11 



2.85 



2.39 



.42 



.48 



1.10 



18.97 



11.62 

 .06 



100.00 



Numbers 1, 2, 4, 5, and 6 analyzed by F. A. Genth. 



Number 3 by A. S. McCreath. 



Number 7 by John I. Thompson, Lemont, Pennsylvania. 



Some of the dissolved silica may enter into chemical combination with 

 the iron ; some of it may simply be carried down with the iron in minute 

 particles. The deposition of the iron in the presence of minute particles 

 of clay might inclose some of the particles without any chemical action, 

 and the association be so close and the included particles so minute that 

 they could not be separated by any mechanical means. The phosphorus 

 may occur in combination with the iron as vivianite, triplite, or some of 

 the associated forms, or perhaps as a basic ferric phosphate, or it may 

 be in combination with the alumina. Evidence favoring the latter sup- 

 position is the prevalence of wavellite, which occurs in large quantities 

 closely associated with the ores in several localities (see page 483), and 

 the occurrence of ceruleolactite in the ore mine in Chester valley. 



The phosphorus will probably form a hydrous phosphate, whether it 

 combines with the iron or the alumina. The remaining alumina prob- 

 ably is in combination with silica and water. This will not leave suffi- 

 cient water to form limonite with all the iron, in the molecular ratio 

 commonly given, namely, 2Pe 2 3 , 3H 2 0. In fact, if all the water com- 



* Insoluble residue. The analysis of the insoluble residue in number 7 gave : Si0 2 = 13,505 

 A1 2 3 2.4, CaO .078, MgO .147. 



