r>4r-A Palache and Warren — Chemical Composition and 



material had undergone considerable alteration with consequent 

 changes in composition. 



Relation, of Synchisite to Parisite. — The synchisite of Flink 

 differs in most respects but little from parisite, and was indeed, 

 but on insufficient material, earlier described as such by Nor- 

 denskiold. The present writers, in view of the results of 

 this study of parisite, believe that no valid distinction exists 

 between these substances, and that synchisite must stand as a 

 synonym for parisite. 



Synchisite is rhombohedral with forms which permitted of 

 only approximate measurement, on the basis of which they 

 were interpreted in terms of the parisite axes. Most of these 

 rhombohedral forms have now been found on parisite, but the 

 new position chosen for the latter requires a readjustment of 

 the symbols as given by Flink. This is made in the following 

 table, it being understood that the angle given for synchisite 

 forms, in each case, is that of the nearest then known form of 

 parisite to the measured angle, none of the latter being given : 



Synchisite (Flink) 





Parisite equivalent 











(Palache) 



c (0001) 







c 



(0001) 





m (1010) 







m 



(10l0) 





n (1120) 







a 



(1120) 





z (1121) 



81° 



33' 



z 



(5.5.10.3) 



81° 12' 



t (2029) 



40 



48 



d 



(0338) 



39 59 



r (2023) 



68 



53 



V 



(0665) 



69 34 



V (3034) 



71 



04 



A 



(0554) 



70 19 



p (1011) 



75 



34 





(0553) ^| 



y 



74 59 

 not found 



s (4043) 



79 



05 





(0773) J 



79 09 



a (3032) 



80 



13 



w 



(0552) 



79 52 



i (0115) 



37 



51 



F 



(1013) 



36 42 



u (0229) 



40 



48 



G 



(5.0.5.13) 



40 46 



q (0112) 



62 



46 



J 



(7078) 



62 56 



y (0334) 



71 



04 



M 



(4043) 



71 28 



j8 (0332) 



80 



13 



P 



(11.0.11.4) 



80 46 



y (0331) 



85 



06 



T 



(5051) 



80 53 



It is evident that the form series of synchisite fits into that 

 of parisite perfectly, and as both are rhombohedral no dis- 

 tinction of form can be made. The new determination of the 

 optical constants of parisite has shown that the two substances 

 have sensibly the same values. Parisite has been shown to 

 have the same cleavage property which Flink showed to be 

 characteristic of synchisite ; the basal cleavage of both is vis- 

 ible only in altered specimens, the fresh minerals breaking with 

 conchoidal fracture. 



