2019-11-082022-02-032019-11-082022-02-03https://hdl.handle.net/11124/173397Donor: Colorado Mining Association.Illustration of a cross-section of an underground mine, showing activities at different levels and car transportation.Caption reads: "Figure 3."10 x 8 inchesblack-and-white photographsCopyright retained by Colorado Mining Association.Mining -- Diagrams and illustrationsUnderground miningMineral industriesIllustration of a cross-section of a mineStillImage