The Luna 24 highland component

Highland lithologies represent a very small but significant component of the Luna 24 drill core. They consist predominantly of melt rocks and glasses of probable impact origin, which are distinguished from their mare counterparts by their CaO/Al2O3 (weight) ratios no more than 0.8 and Fe/(Fe + Mg) (atomic) ratios of no more than 0.4. Compositions equivalent to highland basalt dominate the melt rock and glass fraction. Minor lithologies include possible plutonic lithic and monomineralic fragments. The high proportion of highland basalt relative to the other highland lithologic types, the absence of KREEP basalts, and the low KREEP content of the highland melt rocks and glasses in the Luna 24 soil are also characteristic of the Luna 20 site located in the highland terrain south of Mare Crisium.