AZURITE CRYSTALS FROM MINERAL HILL. 



283 



From the averages thus obtained we derive the following 

 constants: 



Form. 



a 



G 



P 



Obs. 



c(001) 







87 35 18 



20 



P (021) 





•88550 



87 33 4 



14 



/(OH) 



... 



•88578 



87 34 16 



17 



I (023) 





•88603 



87 35 39 



10 



TO (110) 



•85762 







56 



iv (120) 



•85642 







16 



k (221) 



•85727 



•88578 





14 



s(lll) 



•85629 



•88553 





4 



/>(223) 



•85799 



•88743 





5 



R (241) 



•85653 



•88559 





17 



By weighting these values according to the number of 

 observations we obtain the elements: — 



a:b:c = '85721 : 1 : '88581, /? = 87° 34J'. 



Below are tabulated, for comparison, the elements 

 obtained by different authors: — 



Author. 



Locality. 



a 



c 



P 



Schrauf 



Chessy 



•85012 



•88054 



/ // 



87 36 



Lacroix 1 



Chessy 



•8469 



•8789 



87 39 



Gonnard 2 



Chessy 



•8477 



•8792 





Farrington 



Arizona 



•85676 



•88603 



87 36 36 



Cohen 



Broken Bill 



•85608 



•88585 



87 38 



Manasse 



Calabonna . . . 



•85755 



•88803 



87 41 



Anderson 



Mineral Hill 



•85721 



•88581 



87 341 



From this table it is apparent that the axial ratios for 

 the azurite of Arizona, Broken Hill, Calabonna and Mineral 

 Hill are in close agreement and differ considerably from 

 those of the Chessy azurite in which the values for both a 

 and c are smaller. The difference may be emphasized as 

 follows: — 



a 

 c 



Chessy. 

 Highest Values. 



Difference. 



Other localities 

 Lowest Values. 



Difference. 



Other localities 

 Highest Values. 



•85012 

 •88054 



•00596 

 •00527 



•85608 



•88581 



•00147 

 •00222 



•85755 

 •88803 



1 Lacroix, Min. de la France et de ses Colonies, in, 1901, p. 751. 

 2 Gonnard, Bull. Soc. fr. Min., xxxin, 1910, p. 248. 



