F. A.Genth — Contributions to Mineralogy. 



201 



that of a partly altered scapolite. They are tetragonal with 

 0/\2=129%°. The following planes have been identified : 0, 

 i-i, 2, 2-i, 2-2, 6-3, the last two hemihedral. Almost entire 

 absence of cleavage, luster vitreous to resinous; H. = 5-6; 

 Spec. gr. = 3-050-3-057. 



An analysis, made by Mr. Reuben Haines gave, after deduct- 

 ing admixed calcite : 







Oxygen ratio. 





Si0 2 



= 36-74 



0-612 



z= 6 



Al 2 O s - — 



19-79 



0*190 



2 



Fe„0 3 __-. 



1-33 







Cat> 



38-16 " 







MgO 



0-77 







Na„0 .... 

 K s O 



0-32 

 0-17 



0-736 



7 



P 2 5 



2-49 







HO..... 



0-23 







Quantivalent ratio of bases {in which he includes P 2 6 — 

 F. A. G.) to SiO„=9 : 6 = 3 : 2, thus making the mineral a sub- 

 silicate. 



Professor Lewis concludes his article thus : " The species 

 appears to be isomorphous with sarcolite, but its very different 

 physical and chemical characters indicate either a distinct 

 species or a pseudomorph. The absence of cleavage and the 

 heterogeneous microscopic characters argue pseudomorphism. 

 Chemically it is allied to gehlenite. The temporary name 

 ' cacoclasite,' referring to its imperfect cleavage was suggested. 

 The specimens are still under investigation." 



I have no information that anything in addition to the above 

 was done by Professor Lewis, and as the whole tenor of his 

 communication leaves a great deal of doubt about the nature 

 of this mineral, I have, at the suggestion of Professor G. 

 Christian Hoffmann, chemist and mineralogist of the Canada 

 Geological Survey, made a few experiments with excellent 

 material which he had given me for this purpose, also with a 

 crystal which Dr. A. E. Foote kindly presented to me, and 

 give in the following the results of my investigation. 



The calcite, in which the cacoclasite crystals are imbedded, is 

 of a pale blue color and shows perfect cleavage, producing 

 cleavage crystals up to 10 mm in size ; the cacoclasite crystals 

 vary from 3 mm to about 50 mm in diameter ; their surface is 

 glossy and has the appearance, as if the crystals had undergone 

 a partial melting or vitrification. They are more or less 

 rounded, the planes, without exception, are not smooth but 

 deeply corrugated and grooved in an irregular manner. It is 

 remarkable that this peculiarity must have existed, before the 



