Abstract
The Sulphur Bank Mercury Mine (SBMM) was mined intermittently over 92 years from 1865 until 1957. The mining activity on the site produced roughly 2.5 million cubic yards of waste material and various open pits (U.S. EPA, 2023). Early mining activity consisted of extraction of elemental S from surficial deposits, then deep vertical shaft mining that extracted cinnabar from ore bodies at depth, and finally the progressive development of larger open pits before mining permanently stopped due to economic reasons (Everhart, 1946; White and Roberson, 1962). The various waste piles that remain on the surface of the mine property consist of unprocessed ore, processed ore (tailings/calcines), undifferentiated waste rock, and the Waste Rock Dam (WRD), which appears to have a mix of the waste types. The central goal of this thesis was to characterize the mine waste piles geochemically and mineralogically and to answer the following questions: 1) can the mine-waste signatures be interpreted in the context of the steam-heated hot springs deposit vertical zoning model; 2) do mine-waste signatures reflect the timeline of mining history in mineral and chemical markers that are unique to different vertical levels of the original deposit; 3) can the mine-waste signatures provide insight to the source(s) of material that comprises the waste rock dam (WRD), and 4) do elemental abundances in mine waste generally correlate with mineralogy?
The waste piles were grouped into the following four categories: Ore (both the east and west ore piles), TP-SW (the tailings pile, south waste pile, and two hand samples of cinderblock and scoria), WR (the north waste pile, northwest waste pile, and west waste pile), and WRD (drill core material derived from the waste rock dam). These waste “types” were then used to run statistical tests that evaluate differences in mineralogy and chemistry. The data presented in this thesis support the notion that the mine waste types possess distinct signatures. The following minerals appear to be the most important for distinguishing between the waste types: alunite, amorphous silica, buddingtonite, goethite, hematite, jarosite, kaolinite, mica, plagioclase, pyroxene, and quartz. The following major elements are important for distinguishing between waste types: Ca, Fe, K, Mg, P, and S. The trace elements that are important for characterizing the waste types are As, Ba, Co, Cs, Ge, Li, Mn, Ni, Rb, Sn, Tl, W, and Zn. All the REEs besides La appear to be effective for characterizing the waste types: LREEs Ce, Pr, Nd, Sm, Eu, and Gd, and HREEs Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y. The REE data together with mineralogy, major oxides, and other trace elements, make it clear that Ore and WR are similar and tend to group whereas TP-SW and WRD share similarities. Comparing mineralogy between these lumped groups, a trend emerges that suggests the Ore and WR material may have been derived from the more heavily altered Bleached and Boulder zones, the steam-heated zone of the SBA (Everhart, 1946; White and Roberson, 1962); the TP-SW and WRD material may have originated from deeper in the deposit, from the less intensely altered Basal zone of the SBA down into the Franciscan Complex. From this conclusion, it is suggested that TP-SW and WRD material are reflective of material that was extracted during deep vertical shaft operations and/or the later stages of open pit mining, whereas the Ore and WR material is reflective of the earlier stages of open pit mining, which focused primarily on the heavily altered andesite.