Timing is the wonder of wonders. Since I was also working on some encaustic pieces for the first time, and always willing to experiment for a good cause, I tried coloring the stone with epoxy pigments thinned with denatured alcohol to cover up the ugly area. Then, I covered those areas with bee's wax to fill the voids and mellow the colorings. A little color, a little wax, back and forth, and I had a new sculpture. I was very happy with the end results and plan to continue the experiment on other pieces.
The wax has a melting point of 140º f so it should hold up outdoors, but I'll wait for my test pieces to go thru a full year before risking the sculpture. I like experimenting - but with a little caution on the side.