Mining in the Viola Quadrangle
Mining in the Viola Quadrangle was generally in the Rock Island Coal, a lenticular coal that ranged from less than 1 ft thick up to 4 to 5 ft thick within a short distance. The coal was generally present as an upper bench of hard, bright coal 1 to 1.7 ft thick with a lower thicker bench duller coal, separated by a carbonaceous shale 10 to 18 inches thick.
The largest mines were along the western quadrangle boundary and all closed in 1910 or before. There are no known maps of these four mines: Alden No. 1 Mine (mine index 6108), Alden No. 2 Mine (mine index 2973), Empire No. 1 Mine (mine index 2963), and Empire No. 3 Mine (mine index 0290). Their outlines are from a secondary source drawn in the 1930s or estimated by production and shaded as a general area of mining.