GENERAL CHARACTERISTICS OF MINERALS. 15 



are pure and undisguised, ascertains their qualities and their 

 varieties, and thus prepares the mind to recognize them 

 under whatever circumstances they may occur. 



Water has no qualities which should separate it from the 

 mineral kingdom. All bodies have their temperature of fu- 

 sion ; lead melts at 612° F. ; sulphur at 220° F. ; water at 

 32°; mercury at —39°. No difference therefore of this 

 kind can limit the mineral departments. Ice is as properly a 

 rock as limestone ; and were the temperature of our globe 

 but a little lower than it is, we should rarely see water 

 except in solid crystal-like masses or layers. Our atmos- 

 phere, and all gases occurring in nature, belong for the same 

 reason to the mineral kingdom. Several of the gases have 

 been solidified, and we can not doubt that at some specific 

 temperature each might be made solid. We can not, there- 

 fore, exclude any substance from the class of minerals be- 

 cause at the ordinary temperature it is a gas or liquid. 

 Quicksilver with such a rule would be excluded as well as 

 water. 



A mineral, then, is any substance in nature not organized 

 by vitality, which has a homogeneous structure. The first 

 limitation here stated — not organized by vitality — excludes 

 all living structures, or such as have resulted from vital pow- 

 ers ; and the second — a homogeneous structure— excludes 

 all mixtures or aggregates. The different spars, gems, and 

 ores are minerals, while granite rock, slate, clay and the 

 like, are mineral aggregates. This compound character is 

 apparent to the eye in granite, for there is no difficulty in 

 picking out from the mass a shining scaly mineral, (mica,) 

 and with more attention, semi-opaque whitish or reddish par- 

 ticles (feldspar) will be easily distinguished from others 

 (quartz) that have a glassy appearance. 



It is a popular belief, that stones grow. Yet the absence 

 of any proper growth is the main point distinguishing min. 

 erals from objects that have life. Plants and animals are 

 nourished by the circulation of a fluid through their interior ; 

 in plants, we call the fluid sap ; in animals, blood ; and in- 

 crease or growth takes place by means of material secreted 

 from this circulating fluid. The living being commences 

 with the mere germ, and grows through youth to maturity ; 



Why should water and gases rank with minerals. What is a min« 

 ral 1 What limitations are here implied ? What is the nature of 

 grani'e 1 



