"gel box"

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

Samples of Intrusive and Extrusive Igneous Rocks

Hematite-cemented quartz; orthoquartzite.

Chlorite-bearing.

Earthy, porous calcareous tufa.

Fine crystalline, pure calcite.

Classic, very coarse-grained igneous texture.

Represents a Wide Range of Depositional Environments and Rock Textures

Coarse-grained plagioclase and pyroxene with some olivine.

Dark-green 'verde antique', containing some chlorite and calcite.

Dark gray, composed mostly of pyroxene and olivine.

Brownish gray, kerogen-rich; commercial oil source.

Brownish black, intermediate stage between peat and bituminous coal.

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

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

Lustrous, black 'hard coal'.