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1st Student's Major

Chemistry and Geology

1st Student's College

Science, Engineering and Technology

Students' Professional Biography

Ryan Rague is 2013 graduate and recipient of a Bachelor of Science Degree in Earth Science from Minnesota State University, Mankato. While completing his academic curriculum, he focused on researching quartz and magnetite distribution in oxidized iron deposits in the Mesabi Iron Range of Northern Minnesota (2010-2013). His research was presented nationwide, in large part to encouragement and funding from the Undergraduate Research Center, the College of Science, Engineering and Technology, the Department of Chemstry & Geology, and Minnesota State University- Mankato. He was the president of the MNSU Geology Club from 2010-2012 and enjoys promoting progressive and responsible mine geology research and consulting.

Mentor's Name

Steven Losh

Mentor's Email Address

steven.losh@mnsu.edu

Mentor's Department

Chemistry and Geology

Mentor's College

Science, Engineering and Technology

Abstract

Oxidation of iron formation in the Mesabi Iron Range, Minnesota, has negatively impacted recovery of the main ore mineral, magnetite, by two mechanisms. First, magnetite has been partially or completely oxidized to hematite (martite), which is not magnetically separable. Second, silica has been remobilized during the oxidation process, and comprises a higher percentage of the ore concentrate than is desirable due to its altered grain size, making it difficult to grind sufficiently. Fluid inclusion data showed that fault-channeled, diagenesis-stage fluids (mean T homog = 154° C; mean salinity = 9.5 wt% NaCl equivalent) were responsible for early oxidation of iron formation: this event is distinct from later, widespread, shallow-level supergene (lateritic) oxidation. Petrographic and SEM examination of rocks from early-oxidized zones show rims of recrystallized quartz around variably-oxidized magnetite in samples in which Fe-talc and/or minnesotaite have been oxidized to goethite, indicating silica redistribution during oxidation. No such rims have been noted in later (supergene)-oxidized iron formation, implying they may have formed only under diagenetic conditions. Additionally, quartz micro veins have filled fractures formed in magnetite grains caused by faulting in some ore zones. This study focuses on the cause and effect of silica remobilization with an eye to enabling prediction of the ore-waste cutoff in a mine from visual inspection of variably oxidized iron formation.

Creative Commons License

Creative Commons Attribution-Noncommercial 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License

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