Basalt scoria was erupted from the Soda Lake maar in west-central Nevada. The pen points to an olivine phenocryst; the ejecta also contains abundant phenocrysts of plagioclase and less common clinopyroxene, as well as minor grains of magnetite.

Photo by Nevada Bureau of Mines and Geology.

This image is made available under the Creative Commons BY-NC 4.0 license terms.

Soda Lakes