"gel box"

Study the Formation of Different Igneous Rocks

Medium-grained with biotite.

Shiny black volcanic glass showing conchoidal fracture and some spherulites.

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

Classic, dark; from the Columbia Plateau.

Coarse-grained plagioclase and pyroxene with some olivine.

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

Light gray, with flow structure.

Dark gray, with hornblende as the dominant mafic mineral.

Grayish black trap rock.