"Igneous Rock Specimens"

Grayish black trap rock.

Abundant small black phenocrysts in a gray to brown matrix.

Scoria is a dark-colored rock formed from lava with a high gas content.

Classic, very coarse-grained igneous texture.

Dark gray, composed mostly of pyroxene and olivine.

Gray-to-brown basaltic, with over 50% vesicles.

Pale pink felsite, with small sanidine phenocrysts.

Glassy; most specimens float in water.