"Dessus de bouchon"

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

Coarse-grained plagioclase and pyroxene with some olivine.

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

Classic, dark; from the Columbia Plateau.

Pale pink felsite, with small sanidine phenocrysts.

Dark gray with abundant gas pocket vesicles.

Abundant small black phenocrysts in a gray to brown matrix.

Study the Formation of Different Igneous Rocks

Shiny black volcanic glass showing conchoidal fracture and some spherulites.

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

Includes: six each of obsidian, pumice, and basalt. Set of 18.

Common rocks and minerals for testing and identification studies are 2–3cm each.