Despite the best efforts of archaeologists, serendipity often plays a role in the most significant finds. In the case of the Mackinaw Cache, a group of boys hauling gravel on a farm near Mackinaw in 1916 uncovered about 40 spectacular “bifaces” on the slope of a hill just a quarter of a mile from the Mackinaw River. A biface is a stone implement that has been worked on both sides. The boys divided up their treasure and sold their finds to collectors within days. It took collector Frank W. Aldrich of Bloomington some time to locate them and reassemble the cache. Aldrich donated them to the Illinois State Museum in 1948.

News of the Mackinaw Cache spread quickly to the top institutions in the Country. In 1917, Dr. W.H. Holmes, Curator of Anthropology at the Smithsonian Institution wrote, “Undoubtedly, they represent the most skillful work in stone flaking that has yet been found in this country.”

The Illinois State Museum has 35 of the blades in its Illinois Legacy Collection. Of the 31 donated by Aldrich, 19 are notched and 12 are un-notched. The age of the Mackinaw Cache is unknown. Some archaeologists conclude the cache is about 2,000 years old. Others say it may be much older. The blades were manufactured from chert, which can be found in outcroppings near St. Louis.