James St. John: Copper skull (Mesoproterozoic, 1.05-1.06 Ga; Calumet and Hecla Mine, Calumet, Michigan, USA) 1
James St. John: Copper skull (Mesoproterozoic, 1.05-1.06 Ga; Calumet and Hecla Mine, Calumet, Michigan, USA) 2
James St. John: Copper skull (Mesoproterozoic, 1.05-1.06 Ga; Calumet and Hecla Mine, Calumet, Michigan, USA) 3
James St. John: Copper skull (Mesoproterozoic, 1.05-1.06 Ga; Calumet and Hecla Mine, Calumet, Michigan, USA) 4
James St. John: Copper skull (Mesoproterozoic, 1.05-1.06 Ga; Calumet and Hecla Mine, Calumet, Michigan, USA) 5
James St. John: Copper skulls (Mesoproterozoic, 1.05-1.06 Ga; Calumet and Hecla Mine, Calumet, Michigan, USA)
James St. John: Copper skull (Mesoproterozoic, 1.05-1.06 Ga; Keweenaw Peninsula, Upper Peninsula of Michigan, USA) 1
James St. John: Copper skull (Mesoproterozoic, 1.05-1.06 Ga; Keweenaw Peninsula, Upper Peninsula of Michigan, USA) 2
James St. John: Copper skull (Mesoproterozoic, 1.05-1.06 Ga; Keweenaw Peninsula, Upper Peninsula of Michigan, USA) 3
James St. John: Copper skull (Mesoproterozoic, 1.05-1.06 Ga; Keweenaw Peninsula, Upper Peninsula of Michigan, USA) 4
James St. John: Copper skull (Mesoproterozoic, 1.05-1.06 Ga; Keweenaw Peninsula, Upper Peninsula of Michigan, USA) 5
James St. John: Copper skull (Mesoproterozoic, 1.05-1.06 Ga; Centennial Mine, Upper Peninsula of Michigan, USA)
James St. John: Copper skull (Mesoproterozoic, 1.05-1.06 Ga; Calumet and Hecla Mine, Calumet, Michigan, USA) 6
James St. John: Copper skull (Mesoproterozoic, 1.05-1.06 Ga; Keweenaw Peninsula, Upper Peninsula of Michigan, USA) 6
James St. John: Copper skull (Mesoproterozoic, 1.05-1.06 Ga; Keweenaw Peninsula, Upper Peninsula of Michigan, USA) 7
James St. John: Copper skull (Mesoproterozoic, 1.05-1.06 Ga; Centennial Number 6 Mine, Upper Peninsula of Michigan, USA)