This study was designed to compare the effects of two overburden spoil types and various mixtures of the two spoils on the performance of pitch x loblolly hybrid pine (pinus x rigitaeda). Sandstone and siltstone overburden were used to create five rock mix treatments: pure sandstone (ss), pure siltstone (sis), a 2:1 ss-sis mix, a 1:1 ss-sis mix, and a 1:2 ss-sis mix. Tree survival was not affected by rock mix, but growth was greatly affected. The greatest growth response occurred on the ss treatment and decreased as the amount of siltstone increased in the rock mix. The average stem volume of trees on the ss treatment was nearly five times greater than that of trees on the sis treatment. The coarse fragment content of the ss (52 pct) was much lower than the sis (72 pct), thus providing a greater volume of fine earth (<2 mm) for water retention and root exploitation. The ph of the ss was much lower than sis (5.7 Vs. 7.1), and available mn was higher in the ss than in the sis (540 vs. 160 Mg kg-1 foliar mn). The results of this study demonstrate the need to consider the effects of various overburden types on tree growth when forest land is the designated postmining land use.