"Freeze-Dried Specimens"

Volcanic glass with snowflakes embedded throughout.

Lustrous, black 'hard coal'.

Shows porphyritic texture in a fine dark matrix abundant large feldspar phenocrysts. Hand specimen.

Fine crystalline, pure calcite.

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

Grayish black trap rock.

Gray with line crinoid columnal fragments.

Glassy; most specimens float in water.

Samples of Intrusive and Extrusive Igneous Rocks

White and black bands of quartz, feldspar, and biotite; typical foliation.