Sample 82MW0020 is a dolomitic mudrock composed of
layered silicates (~50%), dolomite (20-25%), feldspar (6-10%), quartz
(5-10%), opaques (5-10%), and minor calcite veins. Green "specks" may be
glauconite. Grain size is very fine. Modal percentages are estimated
from x-ray powder diffraction analyses performed by standard methods
(Poppe and others, 2001).