The Geology and Petrography of Crater Lake National Park, 1902
This mineral is to be seen in about one-third of the thin sections studied. It is much less abundant than hypersthene and is inclined to occur in more or less irregular grains rather than in sharp crystals, although the latter are by no means lacking. In color it is a pale green without noticeable pleochroism. It has been noticed to inclose magnetite and apatite. It is younger than hypersthene and also, as a general thing, younger than plagioclase, but is older than hornblende.