56 ON THE PRIMITIVE FORMS OF CRYSTALS. 



8. Octohedron, with a Rectangular Base. 



Nitrate of potash* 

 Topaz. 

 Arragonite. 

 Carbonate of lead. 

 Sulphate of lead * 



Muriate of copper.-Z£rfm. Encyc. vol. vii. p. 478. 



9. Octohedron with a Rhombic Base. 

 Sulphur. 

 Sphene. 



Carbonate of soda. 

 IIId class of PRIMITIVE FORMS. 



CRYSTALS WITH THREE AXES. 



1. Cube, 



Muriate of soda. 

 Boracite. 

 Leucite. 

 Analcime. 



2. Regular Octohedron* 



Diamond. 



Spinelle. 



Alum. 



Ruby copper. 

 Fluor spar. 

 Muriate of Ammonia. 

 Pleonaste. 



* Boumon, and Philips make the primitive form of this 

 crystal a right prism with rhombic bases. 



