8 TERMINOLOGY. 



. 15. SIMPLE MINERAL. 



A single individual, or a part of one, in the inorganic 

 kingdom is called a simple mineral. 



A crystal of Quartz, or a fragment of one is therefore a simple 

 mineral : a distinct concretion of Limestone is likewise a simple 

 mineral. No allusion to the chemical composition of a mineral is 

 to be understood by the term simple : a simple mineral maybe com- 

 posed of a single element as is the fact with regard to a crystal of 

 Diamond, or it may be composed of several as in a crystal of Em- 

 erald. 



. 15. COMPOUND MINERAL. 



An inorganic substance consisting of more than one in- 

 dividual of the same kind is called a compound mineral. 



Examples of compound minerals may be seen in specimens of Fluor 

 made up of many distinct crystalline masses, or in a mass of granular 

 Limestone or fibrous Haematite. They are produced whenever 

 several individuals of the same kind are formed within a common 

 space where the contact is too close to allow of their assuming their 

 regular form. Therefore the individuals which form a compound 

 mineral, do not possess regularity. 



. 16. MIXED MINERAL. 



A mixed mineral consists of two or more simple miner- 

 als of different kinds united together. 



Granite, which is an aggregate formed of Quartz, Feldspar and 

 Mica, is a mixed mineral. Porphyries, Lavas and most Slaty rocks 

 are of the same denomination. With these, Mineralogy has no 

 concern ; it having already performed its duty as respects them in 

 ascertaining the nature of their ingredients, or, in other words, of 

 the simple minerals which compose them. 



