Abundant small black phenocrysts in a gray to brown matrix.
Dark gray with abundant gas pocket vesicles.
Pale pink felsite, with small sanidine phenocrysts.
Classic, very coarse-grained igneous texture.
Dark gray, composed mostly of pyroxene and olivine.
Gray-to-brown basaltic, with over 50% vesicles.
Grayish black trap rock.
Coarse-grained plagioclase and pyroxene with some olivine.
Dark gray, with hornblende as the dominant mafic mineral.
Fine to medium-grained with biotite.
Medium-grained with biotite.
Coarse-grained, with microcline, biotite and horblende phenocrysts.
Shiny black volcanic glass showing conchoidal fracture and some spherulites.
Banded volcanic glass.
Glassy; most specimens float in water.
Light gray, with flow structure.
