"Avantor"

Exemplary display of hexoctahedral crystal shape.

Light gray, fine small clasts.

Brownish black, intermediate stage between peat and bituminous coal.

Classic, very coarse-grained igneous texture.

Gray, fine-grained, massive contact rock.

Fine crystalline, pure calcite.

Compact Plant Fiber Masses.

Dark gray, composed mostly of pyroxene and olivine.

Light gray, fine-grained, well-foliated, schistose.

Gray to brown mudstone with abundant silt.

Gray and poorly sorted, with a gritty texture.

Red-brown to gray, coarse-grained, containing feldspar and mica.

Black, fissile; commonly with carbonized fossil plant impressions.

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

Survey set improves student's recognition of all three major rock groups.

Feldspar group; calcium end member plagioclase crystals in pyroxene matrix.