PART I. 



THE DISTINCTIVE CHARACTERS OF MINERALS. 



Preliminary Remarks : The various bodies which occur in Nature 

 are of two general kinds Organic and Inorganic, respectively. The 

 former constitute Vegetables and Animals, and all bodies of vege- 

 table or animal origin. In the living state, they possess certain 

 structural parts or organs by which they assimilate or take into their 

 substance external matter, and thus increase in bulk or maintain 

 vitality. Inorganic bodies, on the other hand, are entirely destitute 

 of functional organs of this nature. They comprise all products of 

 chemical, electrical, and mechanical forces, acting independently of 

 life; and thus include all metals, stones, and rocks, and also air and 

 water. 



Mineral or inorganic bodies are in themselves, also, of two general 

 kinds. Some possess a definite composition and definite physical 

 characters. Others are mixed bodies or compounds of more or less 

 variable character. The former constitute simple minerals or min- 

 erals proper ; the latter form rocks or rock-matters. In Parts I and 

 II of this Treatise, minerals proper are alone considered. Rocks and 

 rock-producing agencies, come under review in Part III and in suc- 

 ceeding portions of the work. 



Minerals are distinguished from one another by certain characters 

 or properties which they possess : such as form, degree of hardness, 

 relative fusibility, &c. 



Mineral characters are of two principal kinds : physical or external, 

 and chemical, respectively. Physical characters comprise the various 

 properties exhibited under ordinary conditions by mineral bodies : 

 colour, form, <fec., are examples, Chemical characters, on the other 

 hand, comprise the properties developed in minerals by the applica- 

 tion of heat, or by the action of acids or other re-agents, by which, in 

 general, a certain amount of chemical decomposition is effected. 



