The primary occurrence of Mercury is in the mineral cinnabar, Mercury sulphide, which is associated with younger low-temperature hydrothermal systems in regions of late Tertiary orogeny and volcanic activity. Mercury deposits in the Owyhee Basin are located in altered tuff and tufaceous lakebeds that have been silicified to opaline deposits. Erosion and transport of soils from these deposits may result in adsorption of Mercury onto suspended particles. In low pH environments, such as conditions produced in acid mine or acid rock drainage, or in natural low pH environments, inorganic Mercury is converted by anaerobic bacteria to methyl mercury which is more mobile. Significant mining activity has occurred in the Jordan River watershed a major tributary to the Owyhee Reservoir. .
Cinnabar has a very strong absorption in the visible due to a conduction band.
Other low pH, secondary iron-minerals indicative of mining activity will also be mapped as indicators of possible sources of Mercury, as these same processes release methyl mercury into the environment. These low pH, iron-bearing minerals have been successfully mapped and sources of acid rock drainage identified by USGS Spectroscopy Lab and Reclamation, using the Tricorder algorithm at the California Gulch Superfund Site in Leadville, Colorado. There are a number of other local and state agencies participating in the overall investigations and study of the Owyhee Reservoir watershed. This project is important because of several issues. First is the fact that natural mineral sources of Mercury may contribute directly to public heath concerns.