Name:   Olivine Basalt Porphyry

Geologic Name:  None

Reference:  Crawford, R.D., Notes on the intrusive rocks of Boulder County,
Colorado: Colorado Geol. Survey, 1st Rept., p. 31, 1909.

Microscopic characters:  Porphyritic texture.  The rock consists of sharp
phenocrysts of augite, olivine and a few lath-shaped plagioclases in a gound-
mass composed of lath-shaped plagioclase, grains of olivine, augite, abundant
magnetite and crystals of apatite.  Some secondary chlorite is present
in the groundmass.