"Freeze-Dried Specimens"

Gray andesite with phenocrysts of felspar and/or hornblende.

Porphyritic igneous rock containing biotite, feldspar, and hornblende.

Pegmatite is igneous rock similar to granite but with larger crystals.

Sale

Pumice is light colored glassy rock that floats in water.

Dark gray, with hornblende as the dominant mafic mineral.

Fine to medium-grained with biotite.

Classic, very coarse-grained igneous texture.

Medium-grained with biotite.

Light gray, with flow structure.

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