CHAPTEE 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 departments 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 discouragement 

 at the outset by calling attention to the fact that, al- 

 though geology covers so broad a field, and embraces in 

 every department almost endless details, the main prin- 

 ciples, 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, comprising, 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 bow few persons know anything' definite about 

 them. There is no other direction in science where 

 so little work will make the student master of so much 

 ground. 



