The mineralogy and petrology of the Luna 20 soil sample.

The lithologic types found in the soil at the Luna site are characterized, and their mineralogical and petrological significance is discussed. Chemically, the Luna 20 and Apollo 16 soil samples are similar, but the Luna 20 soil is slightly depleted in aluminum and calcium and enriched in iron and magnesium relative to the Apollo 16 soils. This slight difference may be a result of the presence of a minor amount of mare material in the Luna 20 soil and its apparent absence in the Apollo 16 soils.