CHAPTER III 
IMPORTANT ELEMENTS AND MINERALS OF THE 
EARTH’S CRUST! 
ComMMON ELEMENTS 
Characteristics of Elements. — When chemists care- 
fully study a substance, such as a mineral or other 
organic or morganic material, they find it to be com- 
posed of elements, sometimes several combined, some- 
times one alone. ‘These so-called elements are the 
ultimate form to which science has been able to reduce 
1 No attempt is made to treat mineralogy and lithology, but merely to 
bring out some important points in the relation of minerals and rocks to 
geology. 
At this place it would be well, if possible, to introduce laboratory study 
of the minerals and the rocks ; for nothing can be more difficult, unintelligi- 
ble, and dull than the study of minerals and rocks from books ; but by an 
examination of specimens, the student is generally interested and instructed. 
Every teacher can find a few rocks and minerals, either in a gravel bank or a 
stone quarry ; and, for a few dollars, sets of minerals and rocks can be pur- 
chased from either H. A. Ward, Rochester, N. Y., E. E. Howell, 612 17th 
Street, N. W., Washington, D.C., Dr. A. E. Foote, Philadelphia, Pa., or 
other dealers. 
For the short study which is all that most classes would be able to give 
to this subject, a text-book of mineralogy or lithology is not necessary. The 
teacher can find the information needed in the books to which reference is 
made near the end of this book. 
23 
