46 ELEMENTARY GEOLOGY 
The Amphibole and Pyroxene Groups.— While pos- 
sessing distinct chemical and crystalline characteristics 
by which they can be distinguished in the crystal, or 
determined with the microscope, the minerals of these 
two groups have so many resemblances, that without a 
careful study, they cannot be told apart when occur- 
ring as small bits in the rocks.’ 
Fia. 8. 
Hornblende, on the right side, and augite, on the left. 
Of the amphibole group the common representative 
is hornblende; of the pyroxene the common form is 
1The teacher will, of course, understand that this does not apply to 
specimens of the mineral collection, which are carefully selected; but the 
geologist, handling the common rocks, deals with minerals in their usual 
condition, which is that of small size. In the great majority of these cases, 
the mineralogist will not find the distinguishing features unless he applies 
the microscope. So, although quite different, for our purpose they can be 
grouped together. 
