"gel box"

Study the Formation of Different Igneous Rocks

Coarse-grained plagioclase and pyroxene with some olivine.

Medium-grained with biotite.

Classic, dark; from the Columbia Plateau.

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

Shiny black volcanic glass showing conchoidal fracture and some spherulites.

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

Light gray, with flow structure.

Dark gray, with hornblende as the dominant mafic mineral.

Grayish black trap rock.

Dark gray with abundant gas pocket vesicles.

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

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