Two previously unreported varieties of mare volcanic glass have been discovered in Apollo 17 samples. Twenty-three chemical types of volcanic glass have now been analyzed from the six Apollo landing sites. These volcanic glasses, which may be samples of primary magmas derived from the differentiated lunar mantle, define two linear arrays that seem to reflect regional, if not global regularities among the source regions of these melts. Additional systematics among these glasses have been used to estimate the bulk composition of the moon. The results suggest that the refractory lithophile elements (e.g., Ca, Al, Ti, REE, U) are present at abundances of 1.7¿chondrites. The silicate portion of the moon appears to have a major-element composition similar to a volatile (Si,Na,K)-depleted, earth's upper mantle. The theory involving an earth-fission origin of the moon can be tested further through trace element analyses (e.g., Ni) on the volcanic glasses, and through determination of the (N/36 Ar) ratio and noble gas isotopes from primordial lunar gas trapped within vesticles associated with mare volcanic glass.