"The Royce and Frost Mine, located east of Hill Street in the NW1/4 sec. 25, T. 89 N., R. 2 E., was worked for smithsonite and galena. The smithsonite occurred mainly as a vein of massive smithsonite called rock bone by local miners. The vein fills a joint that trends about N. 80oW., and mineralized chimneys characteristic of gash-vein deposits are at joint intersections. The main joint shows minor vertical displacement having the north wall dropped a few inches. This mine is in the second opening zone and is on the eastern extension of the Avenue Top or McNulty crevice, from which galena, sphalerite, and smithsonite were mined." Brown and Whitlow, 1960, p. 62.
Plate 7 mine map.
Dockal 1973, p. 73-79 site map figure 17