Abstract

Crystals of anorthoclase, lime-anorthoclase, potash-plagioclase, and plagioclase (Ab 42.7 to 72.7, An 4.6 to 53.5, and Or 4.0 to 32.0 mole percent) are found as inclusions in lava flows, as loose crystals on the flanks of cinder cones and maar craters, and in the cores of ejected bombs in the upper Quaternary Potrillo Basalt (denned here), south-central New Mexico. Nodules and crystals of olivine-spinel-pyroxene, pyroxene, and amphibole are associated with the feldspar crystals in undifferentiated lava.

The structural state of the alkali feldspar crystals is high, whereas that of the plagioclase appears to range from high to low. The feldspar inclusions probably formed in a deep-seated high-temperature environment.

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