Porphyry, location unknown

This listing is for a classification of igneous rock called a porphyry. This is not a root name, but a texturally based name for any rock with coarse phenocrysts in a finer groundmass. Most commonly used for felsic rocks such as rhyolites, granites, etc.

The groundmass is clearly feldspar and quartz, the black mineral comprising the phenocrysts looks like black tourmaline, although this is unknown as is the location. This sparkly little mountainous rock is naturally rough except for its cut, flat underside.

W 3 1/2 X 2 3/4 X H 1 3/4

PORP10