Origin of pyroxene
Examples from the Web for pyroxene
The rocks are liparites, dacites, hornblende and pyroxene andesites.
There is also a small amount of hematite, pyroxene and sericite.The Long Labrador Trail|Dillon Wallace
It is supposed to have formed by the alteration of olivine and pyroxene in the igneous rocks.
Their pyroxene is principally aegirine or aegirine augite; some of them are rich in melanite.
Both are common alteration products of magnesian silicate minerals such as olivine, pyroxene, and amphibole.