Gallium (Ga) is a common trace metal in rocks and soils. It is used widely in doping semiconductors and producing solid–state devices such as transistors. The average Ga concentration in the Earth's upper continental crust is estimated to be 18.6 milligrams per kilogram (mg/kg) (Hu and Gao, 2008).

In our data, the median Ga concentration is 11.0 and 11.2 mg/kg for the top 0- to 5-cm layer and the soil A horizon, respectively. The median Ga concentration in the soil C horizon is 13.1 mg/kg (see the summary statistics [open in new window]).

Gallium's chemical properties are similar to those of the major element aluminum (Al) and Ga's concentration in soils of the United States correlates strongly with Al (correlation coefficient 0.926). As expected, the two elements have very similar distribution patterns in soils across the conterminous United States. Refer to the discussion of Al for specifics of the interpretation of those patterns.

The distribution of mineral resource deposits with Ga as a commodity (major and/or minor) in the United States, extracted from the U.S. Geological Survey (USGS) Mineral Resource Data System (MRDS) website, can be seen by hovering the mouse here. Statistics and information on the worldwide supply of, demand for, and flow of Ga are available through the USGS National Minerals Information Center (NMIC) website.