The Thoen Stone is a sandstone slab dated 1834 that was discovered in the Black Hills of South Dakota by Louis Thoen in 1887. The discovery of the stone called into question the first discovery of gold and the history of gold mining in the Black Hills; it would mean that gold was discovered in the Black Hills 40 years before the Custer Expedition of 1874 and the subsequent Black Hills Gold Rush. It is currently on display at the Adams Museum & House in Deadwood, South Dakota.