USGS Spectral Library

Note: the interactive USGS Spectral Library has been temporarily disabled and that URL now redirects to this page. Please use the above links to access the report, data, and instructions for downloading and using the data.

Spectral Library Description

Researchers at the USGS Spectroscopy Laboratory have measured the spectral reflectance of thousands of materials in the lab and compiled them in the USGS Spectral Library.

• The spectral library was assembled to facilitate laboratory and field spectroscopy and remote sensing for identifying and mapping minerals, vegetation, and manmade materials.
• For many of the samples, wavelength coverage spans the ultraviolet, visible, near-infrared, mid-infrared, and far-infrared regions (0.2 to 200 microns).
• A wide range of materials are included in the library:
  • Minerals
  • Soils (including rocks, and mineral mixtures)
  • Coatings on rock surfaces
  • Liquids, including mixtures of liquids, water and other volatiles, and frozen volatiles
  • Organic compounds, including biochemical constituents of plants and chemical compounds
  • Manmade materials, including materials introduced into the environment by human activity
  • Vegetation and other biologic materials
• Detailed sample descriptions are provided with the spectra, including the results of X-ray Diffraction, Electron Probe Micro-Analysis, and other analytical methods.

Software for SPECPR Files

SPECPR files provided in the library contain spectra along with linked sample descriptions.

Free software is available for reading spectral library files in SPECPR format:

• PRISM (Processing Routings in IDL for Spectroscopic Measurements)
  • A graphical user interface for working with spectra in SPECPR files (such as the USGS spectral library).
  • Can be installed as a plug-in to ENVI.
  • Can run as an IDL Virtual Machine application without need for an ENVI license.
  • Includes a programmer’s interface so that functions can be called from user’s code.
  • Users can define and search for character strings (keywords) in the titles of spectra and/or in their associated metadata descriptions.
• SPECPR (SPECtrum Processing Routines)
  • A command line interface for SPECPR files.
  • Has a macro scripting capability.

Both software packages run in UNIX, LINUX, Microsoft Windows, and Apple Macintosh operating systems.

These programs allow users to:

• plot spectra
• read sample descriptions
• analyze spectral features
• convolve spectra to the characteristics of other spectrometers and sensors
• export spectra to other file formats

Superseded Spectral Library Versions

NOTE: USGS Spectral Library Version 7 supersedes older versions of the library. Learn more about superseded versions.