80 



MINERALOGY 



If solution is allowed to continue for a longer time, the outlines 

 of the individual pits will meet and the face is then often covered 

 with characteristic hillocks, representing points where the walls of 





(\ 



the etch figures have not as yet joined. The sides of the etch fig- 

 ures represent possible crystal faces, or more correctly vicinal faces, 

 and they therefore reflect and conform to the symmetry of the 

 face. Their shape will depend upon the chemical compound, the 



