  A number of dark matter candidates have been discussed that are macroscopic,
of approximately nuclear density, and scatter ordinary matter essentially
elastically with approximately their geometric cross-section. A wide range of
mass and geometric cross-section is still unprobed for these "macros." Macros
passing through rock would melt the material in cylinders surrounding their
long nearly straight trajectories. Once cooled, the resolidified rock would be
easily distinguishable from its surroundings. We discuss how, by visually
examining ordinary slabs of rock such as are widely available commercially for
kitchen countertops, one could probe an interesting segment of the open macro
parameter space.
