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National Coal Resources Data System
US Coal Quality Database



By L.J. Bragg, J.K. Oman, S.J. Tewalt, C.J. Oman, N.H. Rega, P.M. Washington, and R.B. Finkelman


Since the middle 1970’s, the U.S. Geological Survey (USGS) has maintained a coal quality database of national scope. The USGS generated data on more than 13,000 samples on samples collected by the USGS and cooperative state geological surveys. For each sample, 136 parameters are recorded, including data on location and sample description, analytical data from ASTM tests, and USGS tests for major-, minor-, and trace elements. Many of these data have been published in various USGS Open-File Reports or other publications. This CD-ROM contains coal quality data for 7,430 coal samples that represent complete-bed thicknesses at various localities. The CD contains the coal quality data in the COALQUAL database; Landview III TM (data management software) which is integrated with MARPLOT TM ( mapping software); documentation on the software and data; documents pertaining to the collection and analysis of coal samples, as well as to terminology and calculation of coal resources; and various software help files. Help files are on the CD as .pdf files (See list in PDFLIST.PDF) and can be accessed with the Adobe Acrobat Reader software, which is also included on the CD.

It is strongly recommended that the user spend 30 minutes to go through the Quick-Start Tutorial to become familiar with the software to access the COALQUAL data. As the user gains expertise, the longer tutorial covers most of the other functions, in particular mapping functions, that are useful in looking at the data. One of the advantages of this software is that the user can add new data and map sets to the data already on the CD. The next version of the CD, available after the completion of the National Coal Resource Assessment, will contain new analyses, as well as the data collected as part of the assessment. The data are presented on a whole-coal basis, in addition the oxides are also shown as a percentage of the total ash on an ash-basis for specific elements. The standard analyses, American Society for Testing and Materials (ASTM) data are provided on an as-received basis, whereas USGS data are provided on a remnant-moisture basis (using USGS test methods, moisture contents of samples were not adequately determined prior to analysis. Therefore some samples, particularly low-rank coal samples, contained significant amounts of unmeasured moisture which would manifest an effect by reducing the amount of ash, trace- major-, and minor- elements.). Samples have been selected from the USCHEM (USgeoCHEMical) database using the following criteria:

1. GSASH data must have a positive value, not 0, in order to convert data on an ash-basis to a whole-coal basis.

2. GSASH and STDASH data must be less than or equal to 33 percent (as-determined basis).

3. All data must represent complete-bed channel or drill core (SEE list of SAMPTYPE and VALREP values in TECHINFO.PDF. For some localities, data are represented by one sample obtained either by channel or core (Swanson & Huffman, 1976; Stanton, 1989). In other localities, data were calculated from weighted averages of samples taken sequentially to represent the bed thickness. (Weighted averages are calculated by normalizing the data to the total "bed thickness" using the individual sample thicknesses.) 4. Samples must have an ESTRANK (apparent rank) value which is not a rock type. (SEE list of ESTRANK values in TECHINFO.PDF)


This database was prepared by the U.S. Geological Survey (USGS), an agency of the U.S. Government. The information contained in this database has been approved for release by the Director of the USGS. Although the data have been subjected to rigorous review and are substantially complete and accurate, the USGS reserves the right to revise the data pursuant to further analysis and review.

These data included in this database are released on condition that neither the USGS nor the U.S. Government may be held liable for any damages resulting from their use. THE USGS MAKES NO CLAIMS AS TO THE ACCURACY OF APPARENT COAL RANK CALCULATED FROM PARAMETERS OF PROXIMATE AND ULTIMATE ANALYSES. (With some samples calculated rank may be higher due to air-drying of samples before analysis.)

I have read and understand the above statements, and am ready to perform a search of the database

I wish to download the contents of the CD (189Mb - contains database, software, and related documents)

I wish to download Adobe Acrobat reader to view the PDFs

For information regarding this database, please contact Robert Matthias (rmatthias@usgs.gov) or Charles Oman (coman@usgs.gov).

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Last updated 06 April 2006