The WSGS completed its investigation into the iron resources of Wyoming in 2015 with the publication of its Report of Investigations No. 67. The goal of the study was to consolidate and correct information on iron from a wide variety of earlier investigations, the latest of which was published by the U.S. Bureau of Mines in 1976. WSGS RI-67 not only fulfills that goal, but also provides better perspective on iron resources throughout Wyoming along with new site information and multi-element analyses that were previously absent or incomplete.

Iron has been a significant resource in the history of Wyoming, providing raw material, jobs, and economic development. The earliest iron mining and use was by Paleo-Indians in the Sunrise area, in southeast Wyoming for iron oxide pigment between 8,000 and 13,000 years ago. In the late 1800s, Wyoming produced concretionary hematite from the Rawlins area for use as paint pigment and smelting flux.

Sunrise Iron Mine
Main pit at the Sunrise Iron Mine near Hartville. [Credit: Wayne M. Sutherland, WSGS]
Iron concretion
Iron concretion in the Thermopolis Shale south of Laramie. These concretions have been used as a weighting factor in cement. [Credit: Wayne M. Sutherland]

Titaniferous magnetite, identified prior to 1850, has been mined sporadically from magmatic segregation deposits in the Iron Mountain area for use as a weighting additive in cement. Archean banded iron formation (BIF) mined in both the Hartville Uplift, between 1899 and 1980, and near South Pass, from 1962 to 1983, accounted for more than 132 million tons of iron ore, shipped out of state for iron and steel manufacture. Over time, numerous smaller deposits across the state have also been investigated as potential sources of iron.

Wyoming currently has no active iron mines but does have in-place iron ore resources that may have future economic viability. For example, iron deposits at South Pass and in the Hartville Uplift have not been mined out and still contain large amounts of iron ore. Numerous small iron occurrences are known across Wyoming, and recent exploration has identified at least one potentially large and previously unknown deposit in the Rattlesnake Hills-Granite Mountain area in central Wyoming.

All known iron occurrences from various resources have been compiled and summarized in sections of WSGS RI-67. Analytical data is presented within the text of the report, and complete analyses are included in the appendix.

Elemental iron is the fourth most abundant element in the earth’s crust at about 5 percent and is most commonly found combined with oxygen in the form of iron oxide minerals, particularly magnetite and hematite. The demand for iron fluctuates as second and third world countries urbanize and continue developing. Iron will likely always remain a necessity for everyday life on a global scale. It is integral to products that range from paperclips and metal alloys to cosmetics, fertilizer, and animal feed. A wide variety of uses for iron is shown in the following table:

Uses for Iron

Table of uses for iron


Patty Webber,