USGS - science for a changing world

Mineral Resources On-Line Spatial Data


National Geochemical Survey database

Frequently asked questions

  1. Some of the chemical analyses show negative values. What does this mean?
    Negative values indicate a determination that is below the limit of detection for the analytic method used. The magnitude of the negative number indicates the detection limit. For example, -10 ppm means the result should be regarded as < 10 ppm.

Accessibility FOIA Privacy Policies and Notices

USA.gov logo U.S. Department of the Interior | U.S. Geological Survey
Page Contact Information: Peter Schweitzer
Page Last Modified: Tuesday, 20-Dec-2016 12:05:20 MST