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.
Set of Nine Thin Sections and Matching Rocks
Gray-to-brown basaltic, with over 50% vesicles.
Grayish black trap rock.
