This open-file report for Montezuma and Dolores 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-01-18D
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:
Montezuma and Dolores Counties occupy the southwest corner of Colorado, and both are partly to mostly within the Paradox Basin. This evaluation of the mineral and mineral fuel resource potential was conducted for the nearly 59,970 acres of state mineral lands within these two 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 62 individual tracts that range from approximately 40 acres to 11,080 acres.
Oil, gas, and carbon dioxide (CO2) are the most economically significant resources in Montezuma and Dolores Counties. In 1998, Montezuma County was 15th in annual gas, 6th in annual oil production, and 1st in CO2 among Colorado’s 35 gas producing, 30 oil-producing, and 3 CO2-producing counties. Dolores County placed 22nd in annual gas and 11th in annual oil production.
Although there was no active coal mining in either county in 1998, most of the State Land Board tracts are located within either the Nucla-Naturita coal field or the Durango coal field. These operated in the late 1800s and early 1900s. Similarly, as of the time of this report there are no active metallic mining operations in either county, although resources such as uranium, silver, gold, copper, lead, and zinc do exist and have been mined in the past.
Sand and gravel resources and building stone derived from the Cretaceous Dakota Sandstone are the most widespread and readily accessible mineral resources in both counties.