  This paper explores tools for modeling and measuring the compositional
heterogeneity of a rock, or other solid specimen. Intuitive ``variation per
decade'' plots, simple expressions for containment probability, generalization
for familiar error-in-the-mean expressions, and a useful dimensionless sample
bias coefficient all emerge from the analysis. These calculations have also
inspired subsequent work on log-log roughness spectroscopy (with applications
to scanning probe microscope data), and on angular correlation mapping of
lattice fringe images (with applications in high resolution transmission
electron microscopy). It was originally published as Appendix E of a
dissertation on ``Microcharacterization of interplanetary dust collected in the
earth's stratosphere''.
