This open-file report for Grand and Summit Counties includes an introduction to the geology and mineral resources of the county along with an index map of tract locations, map of metallic mineral prospects, industrial mineral locations, and oil and gas test wells and oil field locations. The main body of the report is an evaluation of each individual tract, which includes text as well as a topographic map and a geologic map. Digital ZIP/PDF download. OF-01-06D
Four general categories of resources are included in this inventory:
- oil and gas
- metallic minerals
- industrial minerals and construction materials
Each individual tract evaluation includes:
- A bar graph which ranks each tract’s resource potential for each of the four mineral categories. An explanation of the categories may be found at the end of this introduction
- Tract identifier number, county name, and county location map
- Tract location on a 7-1/2-minute United States Geologic Survey topographic map
- Tract location on a United States Geologic Survey surface outcrop map
- Location as to section, township, and range and approximate acreage
- Overview of tract geology
- Specific assessment of the resource potential for the four resource categories
- References used in assessing tract potential
From the Introduction:
Grand and Summit counties lie between and include parts of the Front Range and Park Range of north central Colorado. This evaluation of the mineral and mineral fuel resource potential was conducted for the nearly 77,000 acres of state mineral lands within Grand and Summit Counties. It was conducted as part of its long-term evaluation of approximately 4 million acres of state lands administered by the State Land Board. For evaluation purposes, the counties were divided into 69 individual tracts that range from approximately 160 acres to 18,325 acres.
There are no known coal-bearing strata in Grand or Summit Counties. Also, there are no oil and gas fields in Grand or Summit Counties. There are several areas in these counties where favorable structures exist and numerous wildcat wells have been drilled targeting the Mesozoic rocks. The best result has been uneconomic hydrocarbon shows.
Summit County is within the bounds of the Colorado mineral belt and includes the prolific Breckenridge placer gold and lode gold districts, Keystone, Montezuma and the Kokomo districts. There are several recorded uranium occurrences, mostly in the Cretaceous sedimentary formations or in Tertiary volcaniclastic rocks in Grand County. Production from Grand County has been minor. There are two reported uranium occurrences in Summit County; both consist of single assays from shear zones or veins in Proterozoic rocks.