A research facility has been established in the granitic gneiss of the CSM Experimental Mine at Idaho Springs, Colorado, for the purpose of evaluating/ developing mining, geologic and geotechnical procedures appropriate for use in establishing nuclear waste repositories in hard rock. An experimental room has been excavated using careful blasting procedures. The extent and magnitude of blast damage is being evaluated. Structural geology is being mapped to assess continuity.


The Colorado School of Mines under sponsorship of the Department of Energy through the Office of Nuclear Waste Isolation has established a hard rock research facility at its Experimental Mine near Idaho Springs, Colorado. This facility which is located in the Idaho Springs formation (a granitic gneiss) is presently being used for the following purposes:

  • evaluate and develop techniques for careful excavation in hard rock.

  • develop the mapping techniques required for adequately describing the structural geology.

  • evaluate the structural continuity in granitic gneiss.

  • evaluate the structural damage done to the rock mass by blasting.

  • develop techniques for evaluating fracture permeability.

  • evaluate the permeability changes in the rock mass due to blasting.

Although specifically oriented towards nuclear waste storage/disposal, the techniques and procedures being developed/evaluated have wide applicability to all underground excavations in hard rock.


The Edgar Mine (the proper name for the CSM Experimental Mine) is located at an elevation of about 2,30Om at Idaho Springs, Colorado, approximately 40km from the CSM campus at Golden.

Geologically, the mine is located in an area which has been varyingly affected by seven tectonic and/or structural events dating back 1.750 b.y. Three of the seven events appear to have played a dominant role in establishing the structural trends present. The Boulder Creek Orogeny (1.750–1.690 b.y.) initially resulted in regional dynamothermal metamorphism of the Precambrian basement rocks and formed a structural trend still existent today. A younger, un-named Precambrian deformation (1.30 b.y.) was dominantly cataclastic accompanied by minor and local recrystallization and folding. A third event during the Late Cretaceous to Early Tertiary time (70–40 m.y.) not only resulted in an undetermined amount of reopening of Precambrian, age fracture sets but also was responsible for superposition of a younger set of fractures on a regional basis throughout the Precambrian basement rocks. The younger Precambrian cataclastic event and the Late Cretaceous-Early Tertiary Laramide Orogeny resulted in the rocks of the central Colorado Front Range having undergone brittle failure. The ores for which the Edgar was developed are thought to have been deposited at that time.

The Edgar Mine was named after the Edgar vein which strikes N65°E on the average and dips 70–85O N.W. It consisted of a crushed wall rock, primarily a schist of the Idaho Springs Formation, from a few inches to three feet in width. It was slightly silcified and contained disseminated pyrite. Records from the 1870's revealed that the first class ores of the Edgar Mine averaged 16 gms/t gold, 151 gms/t silver and seldom less than 45 to 50 percent lead.

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