Chemistry and phase relations of VLT Volcanic glasses from Apollo 14 and Apollo 17

The VLT (very low titanium) volcanic glasses from Apollo 14 and Apollo 17 have been analysed for the major elements and trace Ni. These glasses display compositional trends that may not result entirely from olivine fractionation. The phase relations have been determined experimentally. Olivine is the liquidus phase in the pressure interval from 0 to ∼18 kbar. Pigeonite is the liquidus phase from ∼18 kbar to ≥ 22 kbar. If these VLT volcanic glasses are samples of primary melts that had been in chemical equilibrium with olivine and low‐Ca pyroxene in their source regions, then these liquids were derived from depths of 360–380 km within the moon.