National Coal Resources Data System

US Coal Quality Database

U.S. GEOLOGICAL SURVEY OPEN-FILE REPORT 97-134

Analytical data, sample locations, and descriptive information, analytical methods and sampling techniques, database perspective, and bibliographic references for selected U.S. coal samples

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

During the energy crisis of the mid-1970s the U.S. Geological Survey (USGS), in cooperation with State Geological Surveys, initiated an ambitious project to create a comprehensive national coal information database. This database, known as the National Coal Resources Data System (NCRDS), was to contain information on the quantity and quality of our domestic coal resources. A major objective was to locate, measure, and characterize all of the Nation's coal resources, without regard to bed thickness, depth, location, or quality. An initial goal of the project was to obtain and characterize at least one sample per coal bed from every geographic quadrangle (approximately 50 sq. miles) underlain by coal. During the nearly 20 years since its inception the NCRDS's Coal Quality database has developed into the largest publicly available database of its kind. The data were used primarily by state Geological Surveys, university researchers, and other federal agencies. Recent legislation has stimulated new and broader interest in the Coal Quality database. The 1990 Amendments to the Clean Air Act (U.S. Statutes, 1990) cite more than a dozen elements as potential hazardous air pollutants. The Act requires the EPA to conduct a study of the toxic air emissions from coal burning utilities. The Act also requires the EPA to perform a health risk assessment and to recommend new air toxic regulations, if necessary, to protect human health and the environment.

The COALQUAL database, presented here and in the USGS Open-file Report 97-134, is a subset of the 13,035 samples contained in the NCRDS (National Coal Resources Data System) USCHEM (US geoCHEMical) database, and contains coal quality data in which a complete record represents a coal sample with a possible total of 136 fields. Chemical data for the samples are presented in this database on an AS-RECEIVED, WHOLE-COAL basis. In addition, the oxides are also shown as a percentage of the total ash on an ash basis. Some fields may not contain data and will be represented as NO DATA ENTERED in the text fields or negative zero values (-0) in the numeric fields. Details of sampling methods and analytical procedures can be obtained from the cited references and are contained as viewable documents in this web-site. The TECHINFO document provides a description of each data field in the COALQUAL database and an explanation of all codes that are used. The analytical method(s) is noted for each field of coal quality data.

PLEASE NOTE THE FOLLOWING:

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. (For some samples calculated rank may be higher due to air-drying of samples before analyses).

• All ASTM data are reported to two decimal places unless otherwise noted (SEE TECHINFO). All USGS analytical data are reported to TWO SIGNIFICANT FIGURES, except for GSASH which is reported to 1 DECIMAL PLACE.
• All elemental data are reported in parts-per-million (ppm). (SEE TECHINFO FOR OTHER DATA FIELDS).
• Qualified data are not included in the data base as published. Greater than values have been treated as the value. Less than values have been treated by multiplying the value by 0.7 (SEE CONNOR, 1976 in REFERENCES) and dropping the qualifier.
• NULL values represent zero values which were qualified. Qualified zero values are obtained when a sample was not analyzed for an element, when the element had interference in its analysis, or when an element was not detected during an analysis. The percentage of qualified values for each element was calculated using the original as-received data base (USCHEM).
• This percentage calculation did not include qualifiers which resulted in NULL values. See each element in TECHINFO file.
• Data for elements having more than 25 percent qualified values (Au, Bi, Cd, Cl, Dy, Er, Gd, Ge, Ho, In, Ir, Nd, Os, Pd, Pr, Pt, Rb, Re, Rh, Ru, Sn, Te, Tl, and Tm) should be used with extreme caution and elements with 10 to 25 percent qualified values should be used with care.

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 (12.7 Mb - contains database, software, and related documents)

For information regarding this database, please contact M. Levine, Chief, NCRDS (mlevine@usgs.gov). For information regarding database content, please contact L. Bragg (lbragg@usgs.gov).

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Last updated 01 April 2004