348 ON THE PRIMITIVE FORM OF CRYSTALS. 



Essonite, he will no doubt find, upon re-examina- 

 tion, to belong to the Prismatic System *. 



An agreement so striking between the results of 

 a system purely Crystallographic, and a system 

 purely Optical, cannot fail to be regarded as a de^ 

 monstration of the principles upon which both of 

 them are founded. 



I shall now conclude this supplementary paper, 

 with a Table of the Primitive Forms of Minerals 

 and Crystals, which I have determined from their 

 optical structure. 



Table of the Primitive Forms of Minerals and 

 Crystals hitherto undetermined. 



I. & II. — Rhomboidal or Pyramidal System. 



Hydrate of Magnesia. Nitrate of Soda. 



Arseniate of Copper. Subphosphate of Potash. 



Mica from Kariak, &c. Sulphate of Nickel, ^ Certain 



Apophyllite from Uton. 



. surcomposee. 



Muriate of Lime. 



of Strontian. 



Arseniate of Potash. 



Zinc. J mens, 



Superacetate of Copper and 

 lime. 



Ice. 



* I have reason to believe that Mohs did not examine these 

 two minerals himself, but adopted the primitive forms assign^ ' 

 ed to them by Haiiy. 



