Geochemical analysis of rock samples collected and analyzed by the USGS. This dataset includes and supersedes rock data formerly released as "Geochemistry of igneous rocks in the US extracted from the PLUTO database"

Geochemical analysis of sediment samples from the National Geochemical Database. Primarily inorganic elemental concentrations, most samples are of stream sediment in the continental US and Alaska.

Geochemical analysis of soil samples from the National Geochemical Database. Primarily inorganic elemental concentrations, most samples are from the continental US and Alaska.

Geochemical data for stratigraphic rock sequences containing dominantly fine-grained clastic rocks with appreciable organic carbon (above 0.5 weight percent), usually known as 'black shale facies examples' but including all fine-grained clastic rocks such as argillite, mudstone, claystone, and their low-medium grade metamorphic equivalents. Data are provide in Microsoft Access and tab-delimited text formats.