of Chondrocyte, Humite and Clinohumite. 



195 



Kafveltorp, Sweden. 

 Specific gravity = 3-252-3-265. 



Si0 2 



MgO 



FeO 



F 



H„0 



I. 

 33-36 

 54-23 

 6-66 

 6-74 

 1-63 



II. 

 33-28 

 54-37 

 6-58 

 6-58 

 1-72 



III. 

 33-18 



6-63 



IV". 

 33-52 



6-43 



Average. 



33-33 



54-30 



6-62 



6-60 



Ratio 



•556 

 1-358 



•092 



•347 [ 



1-67^9= '186 



0-556 

 1-450 



0-533 



102-52 

 Oxygen equivalent to F = 2-76 



99-76 



Mte. Somtna, Itcdy. 

 Specific gravity =r 3-194-3-215. 





I. 



11. 



Average. 



Ratio. 



SiO„ 



33-96 



33-78 



33-87 



•564 



M^O 



56-37 



56-55 



56-46 



1-411 



FeO 



3-72 



3-60 



3-66 



•050 



F 



5-09 



5-21 



5-15 



•271 



H 2 



2-92 



2-72 



2-82^ 



-9 = -313 





101-96 





Oxygen equivalent to F 



= 2-16 





0-564 

 1-461 



0-584 



99-80 



In discussing the above analyses it has been assumed that 

 FeO is isomorphous with MgO and hydroxyl with fluorine. 

 The ratios have been collected together in the following table : 





Si0 2 



(MgO + FeO) 



(P + OH) 









Warwick, 



0-563 



1-433 



0-546 = 



1-96 



: 5 



1-90 



Brewster, 



0-561 



1-452 



0-593 = 



1-93 



: 5 



2-04 



Kaiveltorp, 



0-556 



: 1-450 



0-533 = 



1-92 



: 5 



1-84 



Mte. Somma, 



0-564 



: 1-461 



0-584 = 



1-93 



: 5 



1-99 



These all approximate to Si0 2 : KO : (F-f-OH) = 2 : 5 : 2 

 which would give for the formula of chondroclite, Mg 6 (F. OH) 2 

 Si 2 8 or an isomorphous mixture of the molecules Mg 3 (MgF) 2 

 (SiOJ 2 and Mg 3 (MgOH) 2 (Si0 4 ) 2 . The ratio of fluorine to 

 hydroxy], or of these two molecules varies considerably. In 

 the Brewster and Mte. Somma minerals it is nearly 1:1, in 

 Kaf veltorp 2 : 1 and in Warwick 2-J : 1. The specific gravities 

 are very close, varying only between 3165 and 3*265 and, as 

 would be expected, increase with the percentage of iron. 



For a better comparison of the analyses with the theory they 

 are given below after recalculating FeO as MgO and bringing 

 the total to one hundred per cent. 



