l4 GENERAL CHARACTERISTICS OF MINERALS. 



consequently much careful attention is required of the student 

 to make progress in the science. Moreover, a great pro- 

 portion of the mineral species are of no special value, and 

 they occur under so many forms and colors that close study 

 is absolutely necessary in order to be able to distinguish the 

 useless, and avoid being deceived by them ; for such decep- 

 tions are common and often lead to disastrous consequen- 

 ces in mining. 



The science of Mineralogy is, therefore, eminently prac- 

 tical. Moreover, the very existence of many of the arts of 

 civilized life, depends upon the materials which the rocks 

 afford. Besides the metals and metallic ores, we here find 

 the ingredients for many common pigments, and for various 

 preparations used in medicine ; also the enduring material so 

 valuable for buildings and numberless other purposes : more- 

 over, from the rocks comes the soil upon which we are de- 

 pendent for food. At the same time, the student of Miner- 

 alogy who is interested in observing the impress of Infinite 

 wisdom in nature around him, finds abundant pleasure in 

 examining the forms and varieties of structure which miner- 

 als assume, and in tracing out the principles or laws which 

 Creative power has established even throughout lifeless mat- 

 ter, giving it an organization, though simple, no less perfect 

 than that characterizing animate beings. 



What is a Mineral ? It has been remarked that Miner- 

 alogy, the third branch of Natural History, embraces every 

 thing in nature that has not life. Is, then, every different 

 thing not resulting from life, a mineral ? Are earth, clay, 

 and all stones, minerals? Is water a mineral? 



All the materials here alluded to properly belong to the 

 mineral series. The minute grains which make up a 

 bank of clay or earth, are all minerals, and if their charac- 

 ters could be accurately ascertained, each might be referred 

 to some mineral species. It is evident, however, that the 

 clay itself, unless the grains are all of one kind, is not a dis- 

 tinct species, though mineral in composition : it is a com- 

 pound mass or an aggregate of different mineral grains ; and 

 this is true of all ordinary soil and earth. In the same manner 

 very many rocks are aggregates of two or more minerals in 

 ntimate union. Mineralogy distinguishes the species, and 

 nables us to point out the ingredients which are mixed in the 

 onstitution of such rocks. It searches for specimens that 



Is clay a mineral 1 What is the nature of many rocks ? 



