"AP PHYSICS LAB 9 STATIC EQUILIBRIUM."

Gray and poorly sorted, with a gritty texture.

Useful for weathering and erosion, soil formation, porosity and permeability, or other general earth science labs.

Specimens To Supplement the Most Widely-Used College Lab Manual for Physical Geology

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

Shiny black volcanic glass showing conchoidal fracture and some spherulites.

Glassy; most specimens float in water.

Lustrous, black 'hard coal'.