"Freeze-Dried Specimens"

Shiny black volcanic glass showing conchoidal fracture and some spherulites.

Pale pink felsite, with small sanidine phenocrysts.

Dark gray with abundant gas pocket vesicles.

Volcanic glass with snowflakes embedded throughout.

Gray, fine, friable, with abundant small sanidine crystal fragments.

Grayish black trap rock.

Glassy; most specimens float in water.

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

Coarse-grained, with microcline, biotite and horblende phenocrysts.

Samples of Intrusive and Extrusive Igneous Rocks

Gray andesite with phenocrysts of felspar and/or hornblende.

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

Sale

Dark gray, composed mostly of pyroxene and olivine.

Study the Formation of Different Igneous Rocks

Coarse grained and abundant in plagioclase feldspar.

Dark gray, with hornblende as the dominant mafic mineral.