MIXKKALOOICAL NOTES: XO. V, 



-AXDERSON. 



409 



Forms. 



mi 

 ri 



K 



h 



Pi 

 h., 



r., 



Xn 



s., 



u 



001 

 OlO 

 110 

 130 

 012 

 Oil 

 021 

 102 

 111 

 010 



110 



130 

 012 

 Oil 

 032 

 021 

 102 



111 



112.^ 



( 



Calciilatetl. 



Error. 





 58 37 

 28 39 







90 

 58 37 

 57 18 

 f 1 19 

 164 5 

 85 57 

 57 18 



32 42 

 i 1 19 

 \64 5 

 f 1 19 

 \64 5 



90 



19 52 

 35 52 

 55 20 

 30 39 

 54 14 

 90 



19 52 

 35 52 

 47 19 

 55 20 

 30 39 



54 14 

 34 46 



2 

 1 

 4 

 1 



1 



o 



34 

 

 2 



n 



\4 



18 

 3 



7 

 6 

 5 

 8 



(5 



no 



137 





 1 

 5 

 14 

 11 

 1 



Two groups of four crystals, twinned in pairs on r were 

 measured. Denoting the four segments by I, II, III, IV, we 

 have I and II twinned on r, likewise III and IV twinned on r, 

 but although the orientation of III and IV relative to I and II 

 is almost the same in the two groups I have not succeeded in 

 proving it due to twinning on any known face. Appended are 

 the angles obtained between the b pinacoids of the four segments : 



(!)• 



(2). 



(Calculated for r twin 57° 18'). 



^1 A h., 



hi A h., 



bi A ^,1 



bi A b., 



bx A b., 



bi A b, 

 An attempt was made to determine whether the reticulated 



