Coal mines of Colorado, statistical data. 27 pages. Digital PDF download. IS-02D
From the Preface:
The Colorado Geological Survey decided that it is in the public’s best interest to utilize this less formal open-file medium to make these interim data tabulations available as quickly as possible. We hope to publish a more comprehensive, updated 1975 Summary of Coal Resources in Colorado within the next few months. The more formal report will include production figures through 1975 and the latest available information on current or planned industry activity in the eight coal regions of the state.
That publication is Resource Series 3 RS-03 Colorado Coal Directory and Source Book.