(from the China Data Center)

Coal Ash Data:

This is a Point coverage in the format of Shapfile converted from the
S+SpatialStats (MathSoft, 1996), which was originally contributed by Gomez and
Hazen (1970) on coal ash for the Robena Mine Property in Greene County,
Pennsylvania. The data serves to illustrate the geostatistical techniques in
Statistics for Spatial Data (Cressie 1993). The coverage has a total of 208
observations with three variables: X and Y coordinates of points, and core
measurements (in % coal ash).