Myths and Legends of our Own Land, by Charles M. Skinner, [1896], at sacred-texts.com
The stone that juts from one of the high banks of the Missouri, in South Dakota, gives its name to the Standing Rock Agency, which, by reason of many councils, treaties, fights, feasts, and dances held there, is the best known of the frontier posts. It was a favorite gathering place of the Sioux before the advent of the white man. The rock itself is only twenty-eight inches high and fifteen inches wide, and could be plucked up and carried away without difficulty, but no red man is brave enough to do that, for this is the transformed body of a squaw who was struck into stone by Manitou for falsely suspecting her husband of unfaithfulness.
After her transformation she not only remained sentient but acquired supernatural powers that the Sioux propitiated by offerings of beads, tobacco, and ribbons, paint, fur, and game—a practice that was not abandoned until the teachings of missionaries began to have effect among them. Soldiers and trappers think the story an ingenious device to prevent too close inquiry into the lives of some of the nobility of the tribe. The Arickarees, however, regard this stone as the wife of one of their braves, who was so pained and mortified when her husband took a second wife that she went out into the prairie and neither ate nor drank until she died, when the Great Spirit turned her into the Standing Stone. The squaws still resort to it in times of domestic trouble.