Becca Hedges
Geo 3010-01/Geo 4070-01
Dr. MacLean/Dr. Kaiser
8 Feb. 2017
Summit 1
​
Around 1500 BC humans in Asia began to work with iron ore. Over time iron workers spread over the continent. Since then iron has become very important to society. It is used to make cookware, armor, weapons, steel, fish hooks, and many more commodities. In the fall of 1849 Parley P. Pratt an apostle of the LDS church discovered the rich iron deposits in southern Utah while exploring for a route to California. In July of 1850 the then prophet of the church, Brigham Young created the “Iron Mission” which would settle in Parowan and subsequently Cedar City during the following years (Bagley). This mission, appropriately named was for the sole purpose of mining the iron. The group that came down were not able to start mining right away. The first iron furnace was built in 1852 located in Cedar City but was short lived closing in 1855. The second attempt started in 1868 located in Pinto, Utah and closed in 1874. Not much happened from then until the early 1920’s (Wray, 166). In 1880 J.S. Newby, an ore expert of the time came to survey the Iron Springs district. He said this deposit was “perhaps the most remarkable deposit of iron ore yet developed on this continent” and ”probably the largest mass of iron ore in the whole west” (Leith, 12-13). From the 1920’s until recently many companies have owned and operated the mine shipping the ore to northern Utah, Colorado, Wyoming, and even China. It is estimated that aproxamently 100,000,000 lt of iron has been produced from this area to date (Wray, 166-167).
Geologic History
​
There are four peaks known as laccoliths that are associated within this district. The Three Peaks, Granite Mountain, Iron Mountain, and Stoddard Mountain, were formed from igneous intrusions during the Miocene into the limestone country rocks that were deposited during the Carboniferous and Cretaceous ages (Leith, 2). They are almost identical porphyritic quartz monzonite and all of them are iron bearing except the most southern one, Stoddard Mountain, that is of sandstone country rocks. Iron Mountain is where the current mines are located. Three Peaks and Granite Mountain are of a lesser percent ore and not currently economically viable to mine. Iron deposit types found in this area can be classified as reserves unlike Iron Mountain which is more of an actual resource. The Iron Springs district is one of four major mineral belts that formed during the Tertiary age and is located between the Colorado Plateau and the Basin and Range district (Wray, 168). Deformations like folding and faulting occurred during this time which created voids allowing for veins to house the deposits (Leith, 18).
Minerology
​
The Iron bearing minerals being mined are magnetite and hematite which are typical in skarn deposits (Wray, 170). Other minerals like plagioclase, amphibole, biotite, and clinopyroxenes are also found (Barker, 2197-2199). The intrusions are an andesitic composition, the Stoddard Mountain intrusion is more mafic. Along the zones where contact metamorphism occurred minerals mostly of quartz and chalcedony are found near the surface and calcite increases with the depth. Other minerals like garnet, diopside, apatite, mica, hornblende, and other silicates occur as minor minerals. There is high phosphorous and low sulfur, copper, and titanium content in this area. The low sulfur means that mineral like pyrite and other sulfides are not commonly present (Leith, 6-7). Surface deposits from the surface to about 20 ft. down are in pure andesite. There are true vein and fissure deposits. Deposits along the andesite/limestone contact zone are located deeper than 20 feet and are found in large and small masses. There is also a lot of clay material found in this area (Leith, 67). As far as the quality of the ore, the farther down the deposits are the higher grade there will be (Leith, 70).
The intrusions that occurred carried the iron in the magma itself. With the associated heat involved an ore bearing hydrothermal solution process took place. This is known as a supergene process and allows for redox reactions to occur between magnetite and hematite. The chemical process of these reaction types is 3Fe2O3+H2↔2Fe3O4+H2O. This typically occurs in high temperature and pressure conditions with the presence of water. The water source could have been from the magma and or meteoric waters. Magnetite alters easily to hematite in more oxygen rich environments. Banded iron formations are directly related to this process. Hematite will also form in oxic sedimentary environments, mineral hot springs, hydrothermal deposits via oxygenated water or as a weathering product within soils. The iron is always being oxidized and the water is always being reduced. This process can also alter other material or minerals present (Nesse, 394).
​
Another process that can occur in this type of process and deposit type is with pyrite alteration. In the supergene process oxygenated groundwater will react with pyrite altering into iron hydroxides (geothite) while releasing sulfuric acid. An equation of this process is 4FeS2+15O2+10H2O ↔4FeOOH+8H2SO4. The alteration of Fe2+ to Fe3+ can lower the pH of any surface water present. This causes it to be more acidic thus increasing the solubility. The release of sulfuric gasses can aid in forming new sulfur bearing minerals but in its gas form it is harmful to breathe. The sulfuric acid (8H2SO4) can dissolve otherwise insoluble minerals releasing dangerous cations into the groundwater like lead from galena (Nesse, 416-417). Where pyrite is found in very limited quantities this process is not an important impact for this mine.
​
Calcium carbonate (CaCO3) or limestone can play different roles either in the formation of deposits or mining waste. Carbonates are typically insoluble except when involved with alkali metal cations. When this reaction occurs it will open more areas in which vein deposits can be created. Carbonates also act as important buffers in waste material from mining. It will help keep the waste material in a neutral state so long as there is sufficient amounts of CaCO3 present particularly when mixed with H2SO4. Where the Iron Mountain deposits have a low sulfur content this is not as important at this location as in other iron ore mines. Most acids produced in this area would be minimal and the limestone in the area would help neutralize these reactions.
​
Heavy metal contaminants are often associated with mining. Using a phosphate based chemical stabilization process can aid in limiting the leaching of hazardous metals into the surrounding environment. This is called an EcoBond treatment. The EPA has a measure called the Toxic Characteristic Leaching Program (TCLP) which is designed for long term stability of waste material. Positive results have been reported in area that have used EcoBond. (Barthel, 1). Already having a high phosphate content should make this process work well even after the mining processes have been completed.
​
The Iron Mountain mines are open pits because the ore is located close to the surface. There are other deposits in this area that hold the potential of underground mining. Removal of overburden is necessary in an open pit mine. This requires the creation of a mound where the material will be placed (Overview, 4). It creates an eyesore on the landscape and disrupts vegetation. The mounds are prone to erosion but can be contained using an LDC method. LDC’s are an acrylic blended polymeric product that is diluted with available water. The LDC in sprayed on a surface and will form a protecting crust. This has a 100% dust control rating and is low cost. (Enviroseal.com). Reclamation of the mine by filling the pit back in and re-seeding the area would take care of this impact. Clearing material past the water table is also important. This requires pumping of the groundwater out and storing it in another location (Overview, 4). This impact call also be minimized with reclamation. Using the LDC spray can also be a great coating of the pond location before any water is added to it. It creates an impermeable layer preventing the water from seeping down into the ground (Enviroseal.com).
Mining Operations and Impacts
​
During a meeting with Fernley Bryant an old family friend and former employee of the mine while it was owned by Colorado Fuel and Iron Corporation (CF&I) on January 30, 2017, he discussed some of the processes they used. During the blasting phase they would drill down to 33 ft. to take out 25ft of material using upwards of 100 lbs. of nitrogen. From there they would use four different crushers to make a fine powder. The powder was then placed into solution creating a slurry. The slurry was rotated in drums with a magnet on one half of it. This would attract the magnetite and hematite to it and leave the other material in the slurry. He stated that “no pollution was caused during this stage”. Using the railroad the ore was then shipped to the Geneva Steel Plant in Provo, Utah.
​
The mining equipment used and the water consumption create the largest impacts. Fernley Bryant stated that “100 gallons of diesel fuel was used per an 8 hour shift”. All of the hydraulic oil used for the machinery was picked up by a third party and taken somewhere else to be stored. After the mine closed the equipment was just left on site. The water rights in the area are owned by US Steel out of Newcastle, Utah. To limit air pollution outside of exhaust emissions from the heavy machines in use they would spray the roads down with water except for the winter months. They would also reuse any water they could like the water from the washing plant. If any blowouts occurred in the pits they would use filters to catch any oil that may have been there. The mine itself was required to do yearly assessments of all impact they created. Other methods to limit water use could involve the LDC method discussed above. Creating a layer on top of dirt roads and along conveyor belts would limit dust born debris (Enviroseal.com).
Additional Environmental Impacts
​
Other environmental impacts involved with mining involve local wildlife and soils. Most of the animals in this location are deer, rabbits, and other small field animals. This is not an important area in terms of habitat and breeding. No endangered species are located here. The animals could be frightened by the mining activities causing them to leave the area but no long term impact is expected. A common problem that occurs with the removal of overburden is the loss of vegetation. This will allow for more invasive species to take hold and flourish. Proper management of reclamation would limit this impact. Reseeding with local vegetation during multiple stages of the mining process would have the best result. The LDC spray has a 30% increase in crop production (Enviroseal.com). Used in conjunction with reseeding and proper management of reclamation would limit this impact.
​
A socioeconomic impact to consider would include jobs. Cedar City was founded on mining. Though it has become quite diverse between agriculture, tourism, and the university, mining is our history. The population has seen a rise and fall of population but because of its diversity whether or not the mines are open does not affect the town’s stability.
​
Mining can be both good and bad for the land and people. There are some locations that make more sense to mine where others it would be better to just leave alone. To keep up with the demand for resources mining needs to happen somewhere. The least amount of impact we create the better it will be. Proper management of the mining process and consideration of the future are a must. The cleaner the mine, the least damage is created. The least damage created the easier reclamation of the area is. There are many ways to mine with these factors, it really is a matter of just doing it.
Works Cited
Bagley, Will. “Parowan Settled by Mormons 150 Years Ago”. Salt Lake Tribune. [Salt Lake City] 13 Jan. 2001. Final ed., Nation/World sec: A1. Utah history to go. Web. 31 Jan. 2017.
Barker, D. S. "Crystallization and alteration of quartz monzonite, Iron Springs mining district, Utah; relation to associated iron deposits." Economic Geology 90.8 (1995): 2197-217. Web. 30 Jan. 2017.
Barthel, James, and Scott Edwards. "Chemical stabilization of heavy metals." Metals Treatment Technologies MT2 3 (2004): 151-162.
"Interview with Fernley Bryant." Personal interview. 30 Jan. 2017.
Leith, C. K., and Edmund Cecil Harder. The iron ores of the Iron Springs district, southern Utah. Charleston, Washington Government Printing Office, 1908. Web. 30 Jan. 2017.
"Liquid Dust Control Enviroseal LDC PLUS 12™Simply The Best Dust Control Agent You Can Buy." Liquid Dust Control LDC PLUS 12™ is Economical and has an Extra Long Life - Enviroseal Corp. N.p., n.d. Web. 6 Feb. 2017.
Nesse, William D. Introduction to mineralogy. New York: Oxford U Press, 2012. Print.
“Overview of Mining and its Impacts”. Chapter 1. Guidebook for Evaluating Mining Projects EIA’s. Web. 1 Feb. 2017.
Wray, William B., and Alysen D. Petersen. “Iron Resources and Geology of the Property of Palladon Ventures LTD. In the Iron Mountain Area, Iron County, Utah”. Web. 18 Jan. 2017.