World Coal Quality Inventory

Science Center Objects

The U.S. Geological Survey (USGS) Energy Resources Program, in cooperation with many agencies and scientists from the world’s coal producing countries, undertook a project, called the World Coal Quality Inventory (WoCQI), to obtain samples of coal from the world’s producing coal mines during a limited period of time (roughly 1995-2006).

The resulting WoCQI database is intended to help policy makers with decisions regarding:

  • Domestic coal resource allocation
  • Import needs and export opportunities
  • Foreign policy objectives
  • Technology transfer policies
  • Foreign investment prospects
  • Environmental and health assessments
  • Byproduct use and disposal

This can contribute to the most economically and environmentally efficient global use of coal.


International collaborators were provided sample collecting guidelines and forwarded their samples to the U.S. Geological Survey (USGS). Samples were subsequently analyzed for major-, minor-, and trace-elements at the USGS Inorganic Geochemistry Laboratory located in Denver, CO and for proximate and ultimate analyses at a commercial laboratory located in Pennsylvania using ASTM methods (2007). The resulting dataset, in EXCEL 2003 format, includes samples from 56 countries and is not subject to the inter-laboratory variability present in many coal chemistry compilations.


Not all global coal resource occurrences are included in the WoCQI, but 1,580 individual coal samples were eventually collected for analysis. About 70 percent of the WoCQI samples have data from the commercial laboratory, which are presented on an as-received basis. Values for nearly 50 elements from the USGS laboratory were calculated to a consistent dry, whole-coal basis in the dataset.

The WoCQI database is a unique compilation of coal chemical data and in some cases, the WoCQI data may be the only data available for public use. Care must be used when selecting the sample data for use in statistics or interpretation for the following reasons:

  1. There are single samples with little or no spatial variability
  2. There is a mix of sample types and collection methods
  3. The accuracy of the USGS Inorganic Geochemistry Laboratory major-, minor-, and trace-element data is variable