Caps made from reactive materials can present an innovative solution to the problems involved in capping contaminated sediments. Contaminants trying to migrate through a reactive cap will be sorbed, chemically bound, and/or degraded by the reactive material and thus prevented from being released to the water column. Many reactive materials currently being considered have one or more of the following limitations: the materials are too expensive, they are too selective for the multi-pollutant environment prevalent in most contaminated sediments, the reactive materials themselves are toxic to aquatic organisms, or the materials have a low specific gravity and do not settle effectively as a cap. The authors have tested the use of natural minerals, such as ores of aluminum, iron, and manganese, for capping contaminated sediments. A relatively inexpensive mineral, bauxite (aluminum ore), has emerged as the most promising reactive material. In extensive tests with water and sediment from different sources, bauxite effectively sequestered a broad range of contaminants, including mercury, chromium, arsenic, cadmium, nickel, and zinc, as well as certain organic pollutants. Sequestration of these contaminants was relatively unaffected by interferences, such as competing ions and natural organic matter. In toxicity tests, the bauxite proved non-toxic to benthic amphipods, zooplankton, and fish. With joint funding from DoD's Environmental Security Technology Program and EPA's Superfund Innovative Technology Evaluation Program, and with cooperation from the Navy's Engineering Field Activity North East, a field demonstration of this technology is planned to remediate mercury-contaminated sediment at the Navy's Dodge Pond Site in Connecticut. This poster presents the results of bench-scale work and site-specific treatability tests conducted with Dodge Pond sediment.