. 24. PRELIMINARY OBSERVATIONS. 23 



The compound mineral consists of simple ones. It is 

 produced when several individuals of the same quality are 

 formed in a common space, either at the same time, or one 

 after the other ; one being the support of, or at least con- 

 tiguous to the other. It is, therefore, not one simple mi- 

 neral, but a composition of several. If many of these sim- 

 ple minerals come into contact, they prevent each other mu- 

 tually from assuming their regular form. Compound mi- 

 nerals, therefore, which consist of many simple ones, do 

 not possess regularity. 



Examples of compound minerals are frequently met with, 

 as in the above mentioned varieties of rhombohedral Lime- 

 haloide, and paratomous Augite-spar ; also the globular 

 masses of hexahedral and prismatic Iron-pyrites, and the 

 stalactitic masses of rhombohedral Quartz, called Calcedony, 

 &c. may serve as examples of compound minerals. 



. 24. MIXED MINERAL. 



A mineral, consisting of several individuals of 

 different qualities, is termed a Mixed Mineral. 



The mixed mineral consists of simple minerals, like the 

 compound. The mixed mineral, as such, is not an object 

 of Natural History, because its constituent parts, the sim- 

 ple minerals, have already been considered by themselves, 

 and received their appropriate places in the system of Na- 

 tural History. For the same reason it becomes necessary, 

 from the principles of Natural History, to exclude even com- 



exact, if, in the present place, we could avail ourselves of 

 that expression. In order to understand what is meant 

 here, it will be sufficient to consider individuals of the 

 same quality, to be such as are contained in the examples 

 quoted in the preceding paragraph of rhombohedral Lime- 

 haloide, and paratomous Augite-spar. Individuals of dif. 

 ferent quality, are such as exhibit notable differences in their 

 natural-historical properties ; as, for instance, Granite, 

 where the component individuals of rhombohedral Quartz, 

 prismatic Feld-spar, and rhombohedral TaJc-mica, widely 

 differ in appearance and character. 



