Petrography students are expected to write their own descriptions of these thin sections of lunar rock. In general, petrographic descriptions should be strictly objective, leaving all discussion of petrogenesis to the end. However, the petrographic descriptions in this booklet are based on those given in scientific literature and do not necessarily serve as good examples of strict objectivity. Such is the nature of lunar science! In preparing this student booklet, it was important to convey some of the excitement inherent in lunar sample science; thus, some discussion of sample origin has unavoidably crept in. But, remember, it is important to describe nature, before trying to explain it!