A madstone was a much sought-after cure in previous days in North Carolina. This small, curious object was thought to have the power to cure wounds, injuries, and draw out the poison from the bite of a snake or a mad dog.
These small objects were exceedingly rare, a source from the late 19th century attests that there were only "two or three" in the entire world, all of which could happily be found in Eastern North Carolina. This may be something of an exaggeration, recorded encounters with these stones come from all across North Carolina, and even beyond the state's borders, and definitely total more than three. But the objects were exceedingly rare. They were also part of a very long tradition of magical cures.
A madstone is the regional name for a bezoar, a calcified hairball removed from an animal's stomach. When a mass is trapped in an animal's stomach, layers of calcium gradually form around it, and the stomach muscles will compact it into a smooth, round stone. In North Carolina, the deer was the usual animal of choice, and a madstone removed from the stomach of a white deer was thought to be particularly effective.
The use of the bezoar to cure poison was widespread throughout Europe as early as the Fifteenth century. The name bezoar itself comes from a Persian word meaning antidote, and they were in use in the Arabic-speaking world as early as the Eighth century.
The madstone was used to extract the poison after a snakebite or bite from a rabid dog. The stone would be soaked in water and then applied to the wound, to which it would naturally adhere. The stone would be left there until its chalky-white color turned an unpleasant green, a sign that the poison had been removed, and the victim of the bite was supposedly cured. The stone would then be soaked in milk for several hours to restore its natural color.
The madstone was much sought after, and considered highly valuable, so much so that there's at least one incident of a company based out of Virginia selling madstones via mail order in the early 20th Century. The stones would arrive with a complex set of instructions for use, elaborating extensively on the traditional methods of using madstones. Whether the more elaborate ritual around the stone was necessary was rendered somewhat moot by the fact of the unfortunate recipient having received nothing more than a limestone pebble in the mail.
Use of the madstone faded in the early 20th century, helped no doubt by more effective treatments for rabies and the development of anti-venoms for snakebite. But these curious stones still exist in collections across the world, including one which reportedly belonged to Elizabeth I and is included among the collections in the Tower of London.