We knew that the place was ugly and sinister, but feldspar and augite didn't give it that look.
These are distinguished from augite by containing little or no aluminium.
The cones themselves are composed largely of acid andesites, but many of the lavas are augite andesites and basalts.
Sections of augite crystals from the lavas of 1794 and 1820.
augite, however, appears to be more plentiful in the rocks in the form of small roundish grains.
A crystal of augite is shown near the bottom of the drawing.
It is composed of andesitic lavas of the augite type, is pierced by many fumaroles, and has a crater in the solfatara stage.
Hornblende, like augite, also includes a great many minerals.
The augite is mostly a variety of diopside and is only occasionally idiomorphic.
When the crystals are small, it is often difficult to distinguish hornblende from augite.