324 



Spodumene and its Alterations. 



He finds that the precipitate of Li 3 PO" carries down a small 

 and variable amount of its analogue, Na 3 PO', which always 

 renders the figure for estimated lithia too high. 



The differences in these analyses of Spodumene, especially in 

 the amount of oxide of iron, lithia, and the other alkalies, sug- 

 gest that all the material employed has experienced, to a greater 

 or less degree, incipient decomposition or alteration, attended 

 by the chemical and physical effects already described. Even 

 in my own material, this alteration may be indicated by the 

 presence of water and the excess of alkalies, beyond the amount 

 theoretically required for the protoxides. 



Timor diced Constitution. — For the determination of the true 

 theoretical constitution of this mineral, the elementary per cent- 

 ages and ratios have been calculated from the figures of the 

 mean (column marked III), reckoning, Mn, Mg, Ca=2 IV. 



The microscopical examination of the material analyzed, after- 

 wards explained, renders it highly probable that an incipient 

 alteration into Pinite is ind : cated by the water present ; and the 

 proper correction has been made, taking as a basis the amount 

 of water present, and the formula for the Pinite as deduced 

 heyond. 









f 



Atomic. 



Deduct 



for 

 Finite. 





.l.\ JL J.VZO. 





^ 



Quantivalent. 



Si 



29.19 



1043 





1006 



4 



4 



4024 6.3 



Al 

 Fe 



12.55 

 1.36 



459 

 24 



30 



429] 

 24 



- 1.8 



2 



1359 2.1 



Mn 



.65 



12 





12] 









Mg 



1.07 



45 





45 









Ca 

 Li 



.32 

 3.24 



8 

 463 





8 

 463 



2 o 



2 



631 1. 



Na 



.56 



24 





24 









K 



1.15 



2!) 



15 



14 









11 



.045 



45 



45 



J 













49.86 



3116 



150 . 



2966 



11.1) 



12 







JV : 



A] : S 



2 : 



1 : 4 



Hitherto accepted. 

 1.5 : 1 : 3.75 





R : 



Si 



2 



: 1 





2 : 



1 





Na 



(K) : R 1 



pJg. c 



a) : I 



,i 1:3 



: 12 





