The Nonesuch Shale is a Proterozoic geologic formation that outcrops in Michigan and Wisconsin, United States, but has been found by drill holes to extend in the subsurface as far southwest as Iowa.

The Copper Range Company opened the White Pine mine in Ontonagon County, Michigan, in 1955.

The Nonesuch Shale has sufficient organic carbon content (greater than 0.5%) to be considered a potential sourcebed for petroleum.

Oil identified as Precambrian has been found seeping into the White Pine copper mine in Michigan.

[5] Exploration wells have been drilled to Nonesuch-equivalent sediments in the rift basins in Michigan, Wisconsin, and Iowa, but no commercial petroleum deposits have been discovered.