Lunar noritic fragments and associated diopside veins

Fragments composed of coarse (1-2 mm) orthopyroxene (En₇₇Fs₂₀Wo₃En₈₁Fs₁₆Wo₃) and attached plagioclase (An₉₂-An_94.5) are a conspicuous minor component in Apollo 17 soils collected at thebase of the Sculptured Hills. Although the textures of the fragments are ambiguous, they arepossibly plutonic igneous. The fragments are mineralogically similar to rock 78235, a coarse-grained shocked norite with probable cumulate texture. Two of the samples contain small areas of possible igneous mesostasis rich in Si, Al, K, Na, Ba, and P. The apparent restriction of these norite fragments to the Sculptured Hills may indicate that this and topographicallysimilar areas are underlain by coarse-grained noritic igneous intrusions or cumulate bodies.

Veins composed mainly of diopside (En₄₈Wo₄₈Fs₄-En₄₈Wo₄₇Fs₆) with associated chromite (55.6 percent Cr₂O₃), Fe-Ni-Co metal, silica and troilite, and other narrow veinlets of metal, occurin several of the orthopyroxene grains, and appear to result from intrusion and crystallization of fluid (melt or vapor). The source of the fluid is enigmatic.