_Z?. B. Riggs — Composition of Tourmaline. 



41 



Paris. 





1. 



11. 



'~ 



I. 



II. 





I. 11. 



Si0 2 



38-07 — 



38-02 



36-53 



— 



36-42 



35-03 



34-99-3506 



AI0O3 



42-241 





38-10") 







34-44 





Fe 2 3 



- 1 





none 1 

 6-43 [" 

 trace J 







113 





FeO 



•26 [42-44-42-64 







12-10 





P 2 5 



none J 









trace 





MnO 



•35 





•32 







•08 





CaO 



■56 





•34 







•24 





MgO 



•07 





none 







1-81 





Li 2 



1-59 





•95 







•07 





Na 2 



2-18 





2-86 







2-03 





K 2 



•44 





•38 







•25 





H 2 



4-26 4-25 



-4-28 



3-52 : 



3-44- 



3-60 



3-69 



3-63-3-75 



B 2 3 



9-99 9-85- 



-10-13 



10-22 



10-02 



1-10-41 



9-02 



8-92-9-12 



F 



•28 

 100-29 . 





•16 

 99-81 







none 

 99-89 





Less oxygen 



•12 





.07 











100-17 



99-74 



For the Rumford material I am indebted to Mr. E. M. Bailey, 

 of Andover, Maine. The Paris tourmaline was kindly furnished 

 me out of the National Museum collection. 



In connection with the Maine tourmaline the following inter- 

 esting alteration products were studied. A. An alteration 

 from the light green Auburn (B) variety. JB. Flesh-colored 

 alteration from the Rumford locality. C. An alteration from 

 the Hebron rubellite. 





A 



B 



C 



Si0 2 



— 



53-03 



43-90 



A1 2 3 



— 



31-67 



38-71 



Fe 2 3 



— 



•51 



•58 



FeO 



— 



— 



•25 



MnO 



— 



trace 



•04 



CaO 



— 



trace 



•41 



MgO 



— 



trace 



•05 



LioO 



2-86 



•26 



— 



Na 2 



2-16 



•54 



105 



K 2 



9-64 



9-44 



10-92 



H 2 



— 



4-80 



4-25 



B 2 3 



trace 



trace 



trace 



F 







trace ? 



none 











100-25 



100-16 



While the light green Auburn tourmaline were mostly trans- 

 lucent crystals, a few were found, which, having become partially 

 opaque, had assumed a micaceous structure. With scant mate- 

 rial but the above partial analysis was possible. The results 

 indicate a change in the direction of lepidolite. 



The Rumford alteration product was examined microscopi- 

 cally by Mr. J. S. Diller, who observed as follows : " under the 

 microscope it is seen to be composed of two minerals most 



