CHAPTER X. 



HOW TO COLLECT, STUDY, AND PRESERVE MINERALS. 



GEOLOGY, the history of the earth, the science of 

 rocks, fossils, and minerals, is the most comprehensive 

 of all the natural sciences, embracing many depart- 

 ments or subordinate sciences, some of which, like 

 mineralogy, are often studied quite independently of 

 the others. 



It is unnecessary to refer particularly to the interest 

 and practical importance of this world-wide science ; 

 but it is desired to guard the student against dis- 

 couragement at the outset by calling attention to the 

 fact that, although geology covers so broad a field, 

 and embraces in every department almost endless de- 

 tails, the main principles, and the leading facts, are 

 comparatively few and simple. This is even true in 

 what are often regarded as the dryest branches of 

 geology descriptive mineralogy and lithology. To 

 acquire a satisfactory and useful knowledge of these 

 subjects is not a vast undertaking ; for, although 

 geologists recognize many different species or kinds 

 of minerals and rocks, the most of them are very rare 

 and of little consequence in ordinary life. Not more 

 than twenty minerals, and as many rocks, are of the 

 first importance, but these are very abundant, com- 

 prising, so far as we know, at least 999-1000 of the 

 earth. 



These few common minerals and rocks are, in one 

 sense, among the most familiar objects of every-day 

 life, for they are in the fields, walls, houses, and streets ; 

 and yet how few persons know anything definite about 

 them. There is no other direction in science where 



