404 



H. G. FOXALL. 



two crystals above mentioned, owing to the small differ- 

 ences between the ordinates of the [Oil] and the [111] 

 forms. 



With regard to the chemical analysis, it will be seen that 

 the mineral is free from alkalis, and contains small quantities 

 of Ti0 2 , Cr 2 3 , and MnO. It is rather high in A1 2 3 , and 

 iron oxides are present in fairly large amounts. In this 

 part of the work I must express my indebtedness to Mr. 

 H. S. Jevons and Professor Schofield for the use of apparatus 

 and reagents necessary for the accurate performance of the 

 analysis, and also to Mr. T. H. Laby of the Chemical 

 Laboratory for several important hints as to the methods 

 of procedure. 



CRYSTAL I. 



Form 



Measured Angles. 



Goldschmidt'sValues 



Difference. 



</> 



P 







P 



</> 



P 



110 



100 



010 

 011 



43 36 

 43 38 



89 53 



90 00 

 00 



25 52 



O 1 



90 

 90 



89 39 



90 00 

 90 00 

 33 14 



o / 



43 33 



90 00 



00 

 25 43 



91) 00 



90 00 



90 00 

 33 11 



+ 03 

 + 05 

 -07 

 00 

 00 

 + 09 



00 

 00 



-21 

 00 

 00 



+ 03 



CRYSTAL II. 



Form. 



Measured Angles. 



Goldschmidt's Angles 



Difference. 



</> 



P 







P 



* 



P 



-08 



110 



o / 



43 32 



89 52 



43 33 



90 00 



-01 



.»» 



43 39 



90 00 







+ 06 



00 



100 



89 57 



90 00 



90 00 



90 00 



-03 



00 



«> 



90 03 



89 57 







+ 03 



-03 



010 



00 



89 48 



00 



90 00 



00 



- 12 



111 



>5 ON 



33 00 



25 07 



33 04 



+ 01 



-04 



