Haff, J.C.2024-03-142024-03-1410.15786/13688203https://wyoscholar.uwyo.edu/handle/internal/8104https://doi.org/10.15786/13688203Porphyritic diabase, Twin Buttes campground, Sheridan County, Wyominghttps://creativecommons.org/licenses/by/4.0/figure