We collected samples the Fryxell and Bonney Basins of Taylor Valley. In the Fryxell Basin, we collected 2 samples at low elevation near the mouth of Von Guerard Stream and 3 samples at high elevation along the southern valley wall. In the Bonney Basin, we collected 2 samples at low elevation near Wormherder Creek and 2 samples at high elevation along the southern valley wall.To isolate individual apatite grains from soil samples, we used standard sieving, heavy-liquids, and magnetic mineral separation techniques. Grains presented here are all within the 125-250 µm size fraction.To capture images of the grains for the weathering metrics presented here, we used a Hitachi TM3000 scanning electron microscope. We used the software ImageJ to analyze the images.We developed three weathering metrics that characterize grain shape and micromorphology: aspect ratio, percent crystal faces, and chemical etching (pitting index). We defined the aspect ratio as the length of the long axis of the grain divided by the length of the short axis, giving a measure of how elongated grains are. We defined the percent crystal faces metric as the percent of the total visible grain area that was a recognizable crystal face. Our pitting index ranged from 1 (grains with few to no etch pits) to 4 (grains with etch pits covering the entire grain surface).