These data were collected using field portable (handheld) X-ray fluorescence (pXRF) equipped with a 4-watt Ta/Au X-ray tube on two National Institute of Standards and Technology (NIST) certified standard reference materials 2710a and 2711a, a U.S. Geological Survey (USGS) certified standard reference material BHVO-2, and a silicon dioxide blank. These quality assurance data were collected as part of detailed pXRF studies in Hinkley and Water Valleys, 140 kilometers (km) northeast of Los Angeles, California, and as part of a regional geochemical survey in the western Mojave Desert, between 60 to 210 km northeast of Los Angeles. Measurements on National Institute of Standards and Technology (NIST) and U.S. Geological Survey standard reference materials indicated the pXRF was sufficiently accurate for the purposes of these studies for chromium and selected trace elements. Results showed consistent clean (few to no measurable elements) measurements on a silica dioxide blank. Standard reference material indicated a need to adjust instrument beam times to optimize measurements of chromium.