"gel box"

Coarse, 'salt and pepper': dark pyroxene and light andesine. Provides perfect representation of an intermediate igneous rock.

Dark gray with abundant gas pocket vesicles.

Fine to medium-grained with biotite.

Gray andesite with phenocrysts of felspar and/or hornblende.

Abundant small black phenocrysts in a gray to brown matrix.

Samples of Intrusive and Extrusive Igneous Rocks

Classic, very coarse-grained igneous texture.

Dark gray, composed mostly of pyroxene and olivine.

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

Glassy; most specimens float in water.