Abandoned Mines:

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Abandoned Mines
Effects on stream water geochemistry
Fall, 2003 Serena NW Hollmeyer
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Questions...

• What effects to abandoned mines have on pH and
  conductivity?
• What effects will abandoned mines have on
  dissolved metal species downstream?
• Where are the metals seen downstream coming from?
• What impact does pH have on metal dissolution?

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Sample site locations

• Belvidere Asbestos Mine, Eden Mills, VT.
• Ely Copper Mine, Vershire, VT.
• MacIntyre Titanium Mine, Tahawus, NY.

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Belvidere Asbestos Mine

• Eden Mills, VT.
• Asbestos mine
• 1960-1993
• Serpentine, amphibolite, muscovite schist.
• Drains into Dark Branch and Gihon River

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Ely Copper Mine

• Vershire, VT.
• 1821-1950
• Weakly calcareous mica schist with amphibolite
  and acicular amphibolite.
• Pyrite occurrences.
• Drains into Schoolhouse Brook (Upstream and
  downstream samples)

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MacIntyre Titanium Mine

• Tahawus, N.Y.
• 1941-1982
• Ilmenite and magnetite
• Drains into Opalescent River.

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Methods

• Samples collected, filtered and acidified.
• pH and conductivity measured using digital
  meters.
• Samples analyzed using inductively coupled plasma
  optical emission spectrometer (ICPOES).
• Looked for 24 different metals.

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Belvidere Data
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Belvidere Metals
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Ely data
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Ely metals
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MacIntyre data
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MacIntyre Metals
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Analysis

• pH was lowest at Ely (expected due to sulfidic
  mineral exposures increasing acidity)
• Metals were most mobile at Ely, due to low pH?
• Na, Ca, and Mg levels elevated at each site,
  related to bedrock weathering?

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Belvidere samples and possible sources of metals
Calcic filling of fractures?
Amphibole
Serpentine
Road salt runoff?
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Ely samples and possible sources of metals.
Calcareous bedrock
Mica
Copper ore
Amphibole
Road salt?
Feldspar
Associated iron ore
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MacIntyre samples and possible sources.
Feldspar weathering (no road salt input)
Ilmenite
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Conclusions

• pH was lower at sulfidic site.
• Conductivity was highest in pit lakes or
  drainages
• Lower pH created conditions condusive to metals
  leaching

• Bedrock geology ultimately determined metals
  available for leaching.
• Bedrock geology also determined pH, the
  controlling factor in leaching of metals.

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Questions?