Petrologic study of highland rock fragments handpicked from the Apollo 12 coarse fines confirms the KREEPy nature of the A-12 highland components and the importance of norites and alkali anorthosites. This is in contrast to the calcic, non-KREEPy A-16 and A-11 highland lithologies. The results add to the complexity of the igneous lunar highland rocks, which models for the formation of the lunar crust must take into account. A model involving moonwide differentiation followed by serial magmatism and heavy brecciation seems to be required. Results also show that non-KREEPy highland materials are present at the A-12 site and may represent Copernican and Imbrium ejecta, whereas the KREEPy materials may represent pre-Imbrian terra, as at the A-14 site. |