Technical Abstract: Switchgrass (Panicum virgatum L.) is a warm season perennial grass with great potential as a U.S. energy crop. It is widely adapted to many regions of the country, produces large amounts of biomass, and serves as a useful forage grass. Technologies to convert this grass to energy are currently in development and include biological (fermentation) and thermochemical (pyrolysis/gasification) approaches. The objective of this research was to determine whether genotypic variability existed in the accumulation of minerals that impact the suitability of switchgrass for thermochemical technologies. Above-ground biomass samples from six populations grown at five diverse locations were analyzed for a range of minerals including aluminum (Al), silicon (Si), chloride (Cl), potassium (K), phosphorus (P), sulfur (S), and calcium (Ca) and others associated with undesirable combustion characteristics. Differences among populations across locations were complex and suggested that significant environmental factors affected mineral accumulation in these genotypes. The Cl and P content of plant tissues varied approximately five-fold between locations while silicon accumulation varied approximately three-fold. Upland and lowland cytotype explained some of the observed differences, but Population X Location was the primary determinant of variability.