92 HEMITKOPE AND INTE USECTE1) CRYSTALS. 



in character from the primary forms to which they 

 belong, and from which they could not be deduced 

 by any ordinary law of decrement. This class of 

 combined or intersecting crystals generally occurs in 

 arragonite : such forms also frequently occur in car- 

 bonate of lead, in sulphuret of copper, and in other 

 species of minerals. 



