Detailed modal analyses of fifteen surface soils were compared with rake and rock sample data to provide information about source rocks, maturation history, and intrasite variations in Apollo 16 regolith. Triangular plots of source rock components show that, with the possible exception of soils 64501 and 68501. Apollo 16 soils have similar source rocks that are well homogenized throughout the site. Modal abundance variations in submillimeter size fractions tend to reflect those of rake and rock samples. Maturity plots in agglutinate-monomineratic fragment-lithic and crystalline breccia space show Apollo 16 soils to be generally mature except for those collected from trenches (61221 and 61241) and from locations near North Ray Crater (stations 11 and 13). Data produced by other workers is combined with data from this study and used to divide the Apollo 16 site into three soil petrographic provinces. Central site soils are mature, well homogenized, and enriched in glass, but patches of immature and/or inhomogeneous material are also present. They are probably the most typical Cayley Plains materials present at the site. North Ray soils are immature to submature, containing North Ray ejecta in the form of fieldspathic fragmental breccia and plagioclase. South Ray soils are mature, but contain small amounts of fresh impact melts and plagioclase, possibly from breakdown of blocky South Ray ejecta. South Ray and North Ray ejecta differ in composition and physical properties, supporting the hypothesis that the South Ray event excavated Cayley material while the North Ray event excavated Descartes material.