Though more detailed information on the petrography of each lunar sample discussed here can be found in the references mentioned here, basic petrography is stated in Table 2. It should be noted that, due to the strict operational requirements introduced when working with the returned lunar samples, we did not have as much control over selecting precise measurement sites as with the terrestrial samples. The implications of this, as well as the implications of the complex petrology of these samples, are discussed below. However, all analyzed lunar samples had flat, sawed surfaces, meaning that the samples were flush with the instrument window during analysis.