It usually crystallises in igneous rocks which contain much quartz or silica; while augite, on the other hand, crystallises in igneous rocks which are of a more basic character-that is to say, rocks in which silica is not so abundantly present.
"Geology"
James Geikie
There are several other rocks which come into the basic group, but those mentioned are the more common and typical species.
"Geology"
James Geikie
As rationaloids we fully understand the basic attraction which they call magnetic theory.
"The Love of Frank Nineteen"
David Carpenter Knight