The 2005 Intergovernmental Panel on Climate Change report on Carbon Dioxide Capture and Storage suggested that a major gap in mineral carbon sequestration is locating the magnesium-silicate bedrock available to sequester CO2. It is generally known that silicate minerals with high concentrations of magnesium are suitable for mineral carbonation. However, no assessment has been made covering the entire United States detailing their geographical distribution and extent, or evaluating their potential for use in mineral carbonation. Researchers at Columbia University and the U.S. Geological Survey have developed a digital geologic database of ultramafic rocks in the continental United States. Data were compiled from varied-scale geologic maps of magnesium-silicate ultramafic rocks. These rock types are potentially suitable as source material for mineral carbon-dioxide sequestration. The focus of the national-scale map is entirely on suitable ultramafic rock types, which typically consist primarily of olivine and serpentine minerals. By combining the map with digital datasets that show non-mineable lands (such as urban areas and National Parks), estimates on potential depth of a surface mine, and the predicted reactivities of the mineral deposits, one can begin to estimate the capacity for CO2 mineral sequestration within the United States. ?? 2009 Elsevier Ltd. All rights reserved.