The various types of materials that contribute to the lunar regolith are diagrammatically displayed in table 2. To reveal the exploitation potential of the contents of any box requires much additional information. Also of importance is the distribution of the various types of lunar materials. From the simplest point of view, the Moon has two basic types of physiographic provinces: light- colored lunar highlands and dark- colored lunar maria. The highlands are old crust (more than four billion years). The maria are relatively young (less than four billion years) and are large impact-produced craters that are flooded with basaltic rock types (Taylor 1975).
The chemistry of these two basic physiographic provinces is similar, except in aluminum, iron, calcium, and titanium (table 3), but their mineralogy is quite different. The highlands consist of rocks very rich in plagioclase and thus rich in aluminum and calcium; whereas, the maria consist of ilmenite- bearing basaltic rocks and thus are titanium- and iron-rich. The ideal early exploitation target would be situated where both types of materials are juxtaposed, such as near the margins of some mare (McKay and Williams 1979) or on a ray from a major impact that extends from the lunar highlands into a mare.