A properly collected sample that includes the total coal bed interval provides a sample that is a representative cross section of the coal bed at the point of sampling. Core samples are taken for subsequent testing needed for evaluation of coal quality and characterization for commercial evaluations, for planning of mining operations to maintain coal quality, for the determination of coal rank in accordance with Classification D 388, and for geologic coal resource studies.

Note 1-Because of the potential for lateral variability, a sample may not represent the quality of the coal bed at another sample point. The reliability of the data generated from core samples is dependent on the number and spacing of the sample points and the variability of the coal characteristics in a given area.

Moisture determined directly from a core sample shall be considered questionable in any core sample because of possible contamination from drilling fluids and groundwater. If a more representative estimate of the inherent moisture content of the core sample (with the exception of certain low-rank coals) is desired, the sample should be analyzed according to Test Method D 1412.