Highland crust at the Apollo 14 site: A review

Recent petrologic studies of pristine nonmare samples from the Apollo 14 site have demonstrated the unique character of the western highlands crust. Many of the lithologies which occur here are not found at other highland sites or represent unique variations of more common lithologies. Rare highland samples found at the Apollo 12 site have petrologic and geochemical affinities with the Apollo 14 highland suite and the two sites taken together constitute what can be called the Western Highland Province. Rocks of the Western Highland Province are geochemically distinct from similar lithologies found at eastern highland sites (Apollo 15, Apollo 16, Apollo 17, and the Luna sites) -- a fact which adds further complications to current petrogenetic models for the lunar crust. Nonetheless, an understanding of how the Western Highlands Province formed and why it differs from highland crust in the east is crucial to our overall understanding of primordial lunar differentiation and petrogenesis.