344 ON THE PRIMITIVE FORM OF CRYSTALS. 



LIST OF MINERALS 



Which might to have a Primitive Form different from 

 that assigned to them by Hauy. 



Names of Minerals. 



Form according 

 to Hauy. 



True Fundamental 

 Form, as predicted from 

 their Optical Structure. 



Sulphate of Magnesia, ^ 



Right Prism 





VyJ.lI CUlldLC UJi JL_/CilU, ?" 



with a Smi avf* 





Mesotype, J 



base, 





Carbonate of Barytes, ~1| 







of Strontites, s- 



Hexaedral 



r Prismatic System. 



Iolite, j 



Prism, 



Cryolite, "Y 

 Harmotome, 



Chabasie, J 



Obtuse Rhom- 

 boid, 



|> Prismatic System. 



Sulphate of Iron, i 



Acute Rhom- 

 boid, 



|- Prismatic System. 



Essonite, -| 



Right Rhom- 

 boidal Prism 



"j- Tessular System. 



The following Table contains the fundamental 

 forms, as ascertained by Mobs, of those transparent 

 and translucent crystals, in almost all of which I 

 have determined the number of axes of double re- 

 fection. 



