U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2010–3105

October 2010

Understanding Processes Affecting Mineral Deposits in 

Humid Environments

Recent interdisciplinary studies by 

the U.S. Geological Survey (USGS) have 

resulted in substantial progress toward 

understanding the influence that climate 

and hydrology have on the geochemical signatures of mineral deposits and the 

resulting mine wastes in the eastern United 

States. Specific areas of focus include the 

following:

• Release, transport, and fate of acid, metals, and associated elements from inactive mines in temperate coastal areas.

• Release, transport, and fate of metals 

from unmined mineral deposits in tropical to subtropical areas.

• Influence of climate, geology, and 

hydrology on remediation options for 

abandoned mines.

• Application of radiogenic isotopes to 

uniquely apportion source contributions 

that distinguish natural from mining 

sources and extent of metal transport.

Overview

The environmental effects of abandoned mines and unmined mineral deposits 

result from a complex interaction of a variety of chemical and physical factors. These 

include the geology of the mineral deposit, 

the hydrologic setting of the mineral deposit 

and associated mine wastes, the chemistry 

of waters interacting with the deposit and 

associated waste material, the engineering 

of a mine as it relates to the reactivity of 

mine wastes, and climate, which affects 

such factors as temperature and the amounts 

of precipitation and evapotranspiration; 

these factors, in turn, influence the environmental behavior of mineral deposits. The 

role of climate is becoming increasingly 

important in environmental investigations 

of mineral deposits because of the growing 

concerns about climate change.

Identifying the most important processes 

affecting the environmental behavior of mineral deposits is often difficult because of the 

complications arising from multiple physical 

and chemical processes working simultaneously; this identification is essential for effective mitigation or remediation. These distinctions are even more difficult to make in such 

settings as the eastern United States where 

there are seasonal changes in temperature and 

precipitation. Coastal areas are additionally 

challenging because effects involve both fresh 

and sea water. Bulk geochemical techniques 

based on the mass balance of major elements commonly yield ambiguous results. 

Instead, advanced geochemical techniques are 

needed, such as stable and radiogenic isotope 

analysis and trace element analysis of various 

inorganic and organic media. In the context 

of detailed mineralogical and geochemical 

characterization of samples, these techniques 

are needed to isolate or trace the key factors 

controlling the environmental effects of abandoned mines and unmined mineral deposits.

The recently completed USGS project 

entitled “Tracers of Surficial Processes 

Affecting Mineral Deposits in Humid 

Environments” addressed these issues at a 

variety of sites in the eastern United States. 

Results from these studies have increased 

our understanding of the complex interplay 

of physical and chemical processes contributing to the release, transport, and fate of 

potentially toxic elements around unmined 

deposits and abandoned mines in the humid 

climate of the eastern United States. These 

interdisciplinary studies provide the basis 

for scientific decisionmaking for land management and mine remediation agencies. 

The research has involved cooperation with 

a broad spectrum of stakeholders, including 

local, State, and Federal agencies, academia, and nongovernmental organizations.

Current USGS research highlights 

the importance of understanding the role of 

multiple sources and sinks as they relate to 

the flux of metals and other trace elements 

from mine waste piles on the shores of an 

estuary with a submerged, flooded mine pit; 

the effects of warm climates and high rainfall 

on the geochemical signatures of unmined 

copper deposits in mountainous tropical settings; and the implications for remediation in 

temperate climates of the release, transport, 

and fate of a variety of contaminants from 

abandoned metallic and nonmetallic mines in 

the eastern United States. Experts in the fields 

of biology, economic geology, geochemistry, 

hydrology, and mineralogy joined forces for a 

series of studies that investigated these topics 

on scales ranging from the microscopic to the 

watershed. Highlights included the following:

• Integrated detailed geochemical, mineralogical, and radiogenic isotope studies 

of bedrock, ore, mine waste, sediments, 

and aquatic biota (clams, lobsters, crabs) 

at the Callahan Mine Superfund site near 

Harborside, Me., included an inventory 

of the natural and mining sources of 

redistributed metals in sediment profiles 

deposited before, during, and after mining operations within the flooded pit, 

estuarine, and offshore environment.

• Baseline geochemical characterization 

of rocks, surface water, and sediments 

around unmined porphyry copper deposits in the Cordillera Central mountain 

range in Puerto Rico could have important global implications for closure goals 

for porphyry copper deposits worldwide.

• Multidisciplinary studies of abandoned 

metallic and nonmetallic mines in 

temperate climate settings throughout 

the eastern United States demonstrated 

the importance of understanding the 

complex interactions of mine wastes 

with water and the atmosphere for the 

scientific-based decisionmaking process 

for remedial actions at these sites.

• Geochemical and mineralogical studies 

of arsenical pesticides historically used in 

agricultural practices of the eastern United 

States documented the legacy of arsenical 

pesticide use, including the determination 

of diagnostic geochemical and radiogenic 

isotope features to distinguish pesticides 

from natural and mining metal sources.

• A multidisciplinary geochemical, 

hydrologic, mineralogical, and radiogenic isotope study in Pennsylvania of a 

contaminated watershed containing water 

and soils with anomalously high lead and 

arsenic led to identification and apportionment of the natural (bedrock) and anthropogenic (agricultural, anthropogenic, or 

mining) sources of released metals.

• Detailed geochemical, mineralogical, and 

radiogenic isotope studies of soils and 

ground waters in southern Italy focused 

on the processes that controlled metal 

redistribution as a result of changing 

land-use practices, ranging from rural to 

heavily populated urban regions.

Geoenvironmental Studies

Humid Coastal Regions

Metals and acidity are released from 

sulfide-rich mine wastes at abandoned metal 

mines and can commonly be carried for 

many kilometers downstream in fresh water 

watersheds. However, interactions of mine 

drainage with alkaline brackish waters found 
in estuaries generated atypical geochemical 

reactions compared with results expected 

based on well-studied freshwater systems. 

In addition, the growing demand for mineral 

resources and a trend to mine larger deposits 

will likely result in the submarine disposal of 

mine wastes receiving increased consideration 

in the future. Therefore, the results of this 

USGS research on the environmental impacts 

of abandoned mines in the eastern United 

States, including large-scale regional isotopic 

studies of coastal watersheds in Maine and 

New Hampshire (Ayuso and Foley, 2008), 

mineral sources and transport pathways for 

metals release (Foley and Ayuso, 2008), and 

focused studies at the Callahan Mine Superfund site will have far-reaching implications.

In order to examine the flux of metals 

and related compounds from mine waste 

piles onshore to the estuary, samples of mine 

waste, mine drainage, estuary waters and 

sediments, and invertebrates were collected 

and examined in the laboratory for geochemical and other changes that trace the movement 

of these elements (figs. 1 and 2). Methods 

such as electron microscopy, bulk geochemical analysis, geochemical modeling, isotopic 

analysis, laser ablation microanalysis, optical 

microscopy, quantitative x-ray diffraction, and 

surface-area analysis were used to determine 

the complex pathways of contaminants from 

source to marine biota.

Radiogenic isotope variations [lead, 

neodymium, and (or) strontium] and mineralogical and trace element data chronicle 

metal redistribution among host rocks, ore, 

waste piles, estuary sediments, and aquatic 

biota (affecting bivalves and possibly crabs 

and lobsters). Microanalyses of bivalve shells 

collected from sediment cores show distinct 

metal-rich zones and variable metal contents 

for copper, zinc, and lead that closely parallel 

variations in metal contents of enclosing 

sediments. Isotope compositions vary widely, 

linking host rocks, ore, sediment, and clam 

shells. Lead isotopic signatures of sediments 

span a range from host to massive sulfide to 

waste. This isotopic range overlaps signatures 

of bivalve shells and water from the former 

open pit and areas adjacent to the site.

The chemical and isotopic variations 

in estuary sediments reflect core depth, bulk 

mineralogy, and proximity to waste piles. 

The bivalves likely incorporated lead and 

other metals by ingestion of fine particulate 

matter in addition to dissolved metals. The 

lead isotope and trace element data show a 

link between mining and ore processing and 

the fate of metals that are redistributed in 

estuary sediments and aquatic biota. Within 

and immediately adjacent [0–2 kilometers 

(km)] to the site, sediment and shells show 

elevated levels of metals; however, less 

than 4 km away from the mine site, the 

impact of mining is essentially indistinguishable from background levels.

Investigations of the flooded 100-

meter (m)-deep pit in the estuary identified permanent stratification of the water 

column because of the mixing of less dense 

freshwater draining from the surrounding watershed with sea water entering the 

estuary from tidal action. This permanent 

stratification includes anoxic bottom waters 

in the pit where microbial activity converts 

dissolved sulfate in sea water into sulfide. 

This effectively removes metals from the 

water column, overall rendering the metals 

less toxic to the surrounding ecosystem.

The insights gained from detailed 

examination of the Callahan Superfund mine 

site are influencing the decisionmaking process for remediation options at the site and 

can provide sagacity for waste management 

strategies at coastal-setting mines globally.

Land Use and the Legacy of Agricultural 

Practices

Another aspect of this study has been 

to investigate the legacy of land-use evolution, metal redistribution, and the distinction 

between natural and human-derived sources 

on the surface environment. This work has 

involved an assessment of the chemical 

changes in soils and waters in areas that have 

Figure 1. At the Callahan Mine Superfund site on the coast of Maine, the Goose Pond estuary was drained and mined by open pit methods. After the mine 

closure, the pit was flooded. Mining and ore processing activities contributed to the release of metals that are now distributed in host rocks, ore, tailings and 

waste piles, stream and estuary sediments, and aquatic biota. A, Callahan site tailings pile; photograph by Robert Ayuso, U.S. Geological Survey. B, Site of the 

former open pit in 2005; photograph by Robert Ayuso, U.S. Geological Survey. C, Open pit in 1972; photograph by U.S. Environmental Protection Agency.
been affected by agricultural, suburban, and 

urban human activities related to industrial, 

manufacturing, or municipal processes.

The lead isotopic compositions of pesticides commonly used in the United States 

until 1988, such as lead arsenate, sodium 

meta-arsenite, and calcium arsenate, were 

studied in order to better establish anthropogenic sources of lead and arsenic in soils 

and waters. Applying this information to past 

agricultural practices, scientists evaluated 

the sources of lead in residential water wells 

and soils from the former Mohr Orchards 

near Allentown, Pa., a U.S. Environmental 

Protection Agency (EPA) Superfund site 

and an area that has evolved from rural 

to suburban. The levels of lead content in 

residential waters are of concern for possible adverse effects on human health. Lead 

isotopic compositions of surface and well 

waters, arsenical pesticides, local soils and 

bedrock, and other anthropogenic sources 

of lead were measured to identify potential 

natural and anthropogenic sources (Ayuso 

and others, 2008). The well water samples 

show systematic isotope variations. Soils 

enriched in lead and arsenic could have supplied relatively unradiogenic lead to the well 

waters. Lead arsenate pesticide of the type 

that may have been extensively used in the 

area cannot exclusively account for the range 

of lead isotopic compositions of the well 

waters and soils. Industrial lead is favored 

as the predominant source (in addition to 

contributions from pesticide-rich soils) into 

the well waters.

International Land Use Practices

Understanding the impacts of historical land-use practices on modern life is of 

great concern to the national and international community in developing strategies 

to cope with environmental conditions associated with aging rural-to-urban infrastructure. To better understand the global effects 

of environmental conditions, research 

involved joint studies with academic institutions in the European Union that focused 

on soil and water geochemistry.

To examine the processes that control 

metal redistribution as a result of changing 

land-use practices, the chemical composition of surface soil samples, soil profiles, 

and groundwaters in the Campania region 

of Italy were studied. The impact of human 

activity is most intense in the highly urban 

areas (so called brownfields) and least 

intense in rural areas. In urban areas, anthropogenic sources, such as automobile traffic, 

industrial activities, municipal waste, and 

other manufacturing point sources, are likely 

the main causes for the anomalously high 

metal contents (lead, arsenic, cadmium, zinc) 

and unique radiogenic isotope signatures of 

soils and groundwaters. In rural areas, the 

point sources are dominated by metals from 

atmospheric deposition (from industrial processes and from the burning of fossil fuels), 

0

18,000

16,000

14,000

12,000

10,000

8,000

6,000

4,000

2,000

0

1,000

2,000

3,000

4,000

5,000

6,000

206Pb/207Pb

0

500

1,000

1,500

2,000

Zn (mg/kg) Cu (mg/kg) Pb (mg/kg)

MS Background

1.15 1.16 1.17 1.18 1.19 1.20 1.21

1.15 1.16 1.17 1.18 1.19 1.20 1.21

2,500

1.15 1.16 1.17 1.18 1.19 1.20 1.21

Figure 2. Field studies of background bedrock 

and sediments, mine waste materials, and 

estuary sediments and biota were conducted for 

selection of materials for detailed microchemical 

analyses to determine mineralogical and trace 

element variability and to develop isotopic 

tracer methods for discriminating ore from 

natural background conditions. A, Callahan 

Mine Superfund site, Me.; photograph by Robert 

Ayuso, U.S. Geological Survey. B, Pyrite and 

chalcopyrite ore. C, Laser analyses of metals 

in pyrite. D, Arsenic map, showing relative 

microscopic variations in the concentration 

of arsenic; warmer colors (red and orange) 

represent higher concentrations of arsenic, 

whereas cooler colors (blue and green) 

represent lower concentrations. E, Graphs of 

concentrations of lead (Pb), copper (Cu), and zinc 

(Zn), in parts per million (ppm), versus the ratio of 

lead isotopes (206Pb/207Pb); yellow area is massive 

sulfide ore (MS), white area is main field, and 

blue area is the background.
by contributions from past agricultural practices, and by the natural sources of metals 

from the area’s geologic background.

Weathering of Aluminosilicate Minerals

Aluminous minerals occur in a variety 

of mineral deposit types (metallic and 

nonmetallic) found in humid ecosystems. 

Aluminum-hydroxide flocculates in contaminated streams have a close link to aluminumhydroxide solids and are an important 

component of contaminated waterways. The 

degradation of aluminous sources influences 

the mobility of associated metals in mineral 

deposits, mineralized rocks, tailings piles, 

soils, waters, and watersheds because of the 

chemical and thermodynamic properties of 

aluminous minerals.

USGS studies were conducted in 

cooperation with the U.S. Forest Service on 

the weathering cycle of garnet from source 

rock to deposition in garnetiferrous ferricretes and gravels. These studies document 

the impact of primary mineral composition 

on weathering characteristics and resulting 

alteration assemblages. Studies conducted 

in concert with the Conservation Division 

of the National Park Service on the chemical and physical weathering of the Comte 

de Rochambeau monument at Lafayette 

Square Park in Washington, D.C., document 

changes in mineralogy, porosity, surface 

reactions, and specific surface area. These 

parameters may be used to predict degradation rates of carbonate relative to associated aluminosilicate minerals under humid 

temperate, subtropical conditions. Studies of 

mineral reactions, surface area, and correlations with aluminosilicate minerals were also 

conducted in support of the Callahan Mine 

Superfund site and Allentown studies.

Unmined Mineral Deposits in Tropical and 

Subtropical Settings

Unmined mineral deposits are natural 

geochemical anomalies that can manifest 

themselves as geochemical haloes in the 

surrounding rock, in soils, in surface water 

and groundwater, in nearby stream and lake 

sediments, and in vegetation. These manifestations of mineral deposits form the basis 

of the field of exploration geochemistry. 

Most of the knowledge of the environmental 

behavior of porphyry copper deposits, the 

source that supplies most of mined copper 

today, is based on information from deposits 

in semiarid or arid regions, such as Arizona. 

However, because there is significant potential for undiscovered deposits in all climatic 

settings throughout the world, there is a need 

to expand the knowledgebase to behavior of 

deposits in other climatic conditions.

USGS studies around unmined porphyry 

copper deposits in the Cordillera Central 

document the influence of hot climates with 

high rainfall on the environmental expression of porphyry copper deposits (fig. 3). 

Río Pellejas Río Viví

< 32 

 32 - 149

> 149

Piedra Hueca

Calá Abajo

Sapo Alegre

EXPLANATION

Concentration (mg/kg)

Río Pellejas Río Viví

Sapo Alegre

Piedra Hueca

Calá Abajo

< 0.008 

 0.008 - 0.012

> 0.012

EXPLANATION

Concentration (mg/L)

Figure 3. The Cordillera Central of Puerto Rico hosts several unmined porphyry copper deposits. 

A, Photograph of sample site on the Río Viví, Puerto Rico, in the vicinity of deposits; photograph by 

Robert Seal, U.S. Geological Survey. B, Map showing copper concentrations in sediments, measured in 

milligrams of copper contained per kilogram of copper ore (mg/kg). Samples shown as yellow dots have 

concentrations in excess of the threshold effects concentration of 32 mg/kg but below the probable 

effects concentration of 149 mg/kg. Samples shown as red dots have concentrations in excess of the 

probable and threshold effects concentrations. C, Map showing copper concentrations in surface water 

in milligrams of copper contained per liter of water (mg/L). Natural copper concentrations in surface 

waters and springs near the deposits locally exceed short-term (0.012 mg/L) and long-term (0.008 mg/L) 

exposure guidelines set by the U.S. Environmental Protection Agency. Samples shown as yellow dots 

have concentrations in excess of the long-term exposure guidelines but below the short-term exposure 

guideline. Samples shown as red dots have concentrations in excess of short-term and long-term 

exposure guidelines. Black shapes are unmined porphyry copper deposits in figures 3B and 3C. U.S. 

Geological Survey baseline characterization studies of natural geochemical variations in the vicinity of 

the deposits document natural copper concentrations.
The extensive weathering of both the host 

rocks and the mineral deposits has resulted in 

moderately acidic to moderately alkaline pH 

values (5.1–8.9) in the vicinity of the deposits. 

In terms of dissolved constituents, sulfate 

shows significant increases downstream 

of the deposits. Dissolved iron and copper 

only show localized elevated concentrations 

downstream of the deposits. Some of the 

concentrations of copper locally exceed acute 

toxicity limits for aquatic ecosystems. In 

contrast, stream sediments show an extensive 

zone downstream with copper concentrations 

above the probable effects concentration. 

All other elements are below their probable 

effects concentrations (the level of a concentration in the stream sediment that is likely to 

cause an adverse effect from direct exposure) 

(MacDonald and others, 2002).

The results of this research provide a 

better understanding of the environmental 

characteristics of this important type of copper 

deposit under the varying conditions found in 

nature (Berger and others, 2008). Knowledge 

of premining conditions aids in setting realistic 

closure goals for future mines and reasonable 

remediation goals for active and abandoned 

mines that predate modern regulation.

Science in Support of Mitigation and 

Remediation

The chemical complexity of abandoned mines eliminates the possibility 

of a standard method of remediation that 

will solve all or most of the environmental 

problems associated with the mines. The 

variations in chemical complexity from one 

mine to another stem from differences in 

geologic characteristics, mine and ore processing methods, hydrologic settings of the 

mine and the waste piles, and climatic settings. Recently completed USGS research 

investigated the role of climate in controlling the environmental impact of abandoned 

mines in the eastern United States as it 

relates to potential remediation strategies.

Acid-generating mine wastes from 

abandoned base-metal mines in the Virginia 

gold-pyrite belt severely impair watersheds 

downstream of the waste piles. The impairment of the aquatic ecosystem is exacerbated 

by the low total dissolved solids found in the 

watersheds and by evaporative concentration 

of toxic metals during the hot, dry summer 

months. These conditions favor the formation of soluble salts, which can cause acute 

effects during subsequent storm events (Seal 

and others, 2008). Site remediation by State 

agencies includes isolation and encapsulation of mine wastes and submersion of 

residual material to prohibit the evaporative 

formation of toxic soluble salts.

By contrast, acid-generating mine 

wastes from abandoned copper mines 

farther north, in Vermont, can result in the 

formation of toxic metal-sulfate salts both 

on the surface of wastes during hot, humid 

summer months and at depth through 

evaporation. The evaporation is related 

to capillary action throughout the year, 

INSTANTANEOUS STREAMFLOW, IN CUBIC FEET PER SECOND

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER AT 25°C

Figure 4. The weathering of sulfuric mine 

wastes and tailings, as demonstrated in the 

Pike Hill Mine Superfund, Vt., study, cause the 

formation of efflorescent sulfate salts on and 

within waste piles. Spring snowmelt and rain 

events dissolve and flush the highly soluble salts, 

resulting in an increase in specific conductance, 

an increase in dissolved metal concentrations, 

and a decrease in pH in downstream waters. A, 

Mine waste piles at the Pike Hill Mine Superfund 

site; photograph by Robert Seal, U.S. Geological 

Survey. B, Chart showing flushing of efflorescent 

sulfate salts during rain event in October 2005; 

x-axis tick marks indicate midnight of the date 

listed. C, Snowmelt and rain flush salts from 

upstream mine waste; photograph by Richard 

Kiah, U.S. Geological Survey.
even when covered by winter-long snow 

packs (fig. 4). The highest concentrations 

of base-metal contaminants occur in the 

spring with snow melt when water is able 

to saturate the subsurface of the waste 

piles and dissolve the salts (Piatak and others, 2006; Kiah and others, 2007). Future 

site remediation by the EPA could involve 

relocation of the most problematic wastes 

piles, followed by covering to prevent the 

infiltration of water.

Mine wastes from an abandoned 

asbestos mine in northern Vermont have 

caused significant impairment of nearby 

wetland habitats largely owing to the erosion and redeposition of waste material. 

USGS studies documented the formation of magnesium carbonate crusts on 

the waste piles because of weathering 

in humid temperate climates (Levitan 

and others, 2009; Piatak and others, 

2009). These crusts may serve two useful 

purposes. First, the cementation of the 

surfaces of the piles diminishes the amount 

of windblown asbestos dispersed from the 

site to the surrounding areas. Second, the 

crusts represent a sink for atmospheric 

greenhouse gases. Future remedial investigations at the site may need to consider the 

feasibility and positive effects of encouraging these crusts to form under these 

humid temperate conditions.

Summary

The recently completed integrated 

effort of the USGS Mineral Resources 

Program to understand processes affecting mineral deposits in humid settings 

highlights the important role that climate 

plays in controlling environmental effects 

associated with mineral deposits and their 

mine wastes.

References Cited

Ayuso, R.A., and Foley, N.K., 2008, 

Anthropogenic and natural lead isotopes 

in Fe-hydroxides and Fe-sulphates in 

a watershed associated with arsenicenriched groundwater, Maine, USA: 

Geochemistry: Exploration, Environment, Analysis, v. 8, no. 1, February, 

p. 77–89.

Ayuso, R.A., Foley, N.K., and Lipfert, 

G., 2008, Lead isotopes as monitors of 

anthropogenic and natural sources affecting the surficial environment, chap. 12 of

de Vivo, B., Belkin, H.E, and Lima, A., 

eds., Environmental geochemistry—Site 

characterization, waste disposal, data 

analysis, and case histories: Elsevier 

Publications, p. 292–320.

Berger, B.R., Ayuso, R.A., Wynn, J.C., and 

Seal, R.R., 2008, Preliminary model of 

porphyry copper deposits: U.S. Geological Survey Open-File Report 2008–1321, 

55 p.

Foley, N.K., and Ayuso, R.A., 2008, Mineral sources and transport pathways for 

arsenic release in a coastal watershed, 

USA: Geochemistry: Exploration, Environment, Analysis, v. 8, no. 1, February, 

p. 1–17.

Kiah, R.G., Deacon, J.R., Piatak, N.M., 

Seal, R.R., II, Coles, J.F., and Hammarstrom, J.M., 2007, Surface-water 

hydrology and quality at the Pike Hill 

Superfund site, Corinth, Vermont, 

October 2004 to December 2005: 

U.S. Geological Survey Scientific 

Investigations Report 2007–5003, 

61 p., accessed October 15, 2009, at 

http://pubs.usgs.gov/sir/2007/5003/.

For more information, contact

Robert R. Seal

U.S. Geological Survey

954 National Center

Reston, VA 20192

Telephone: 703–648–6290

E-mail: rseal@usgs.gov

Robert A. Ayuso

U.S. Geological Survey

954 National Center

Reston, VA 20192

Telephone: 703–648–6347

E-mail: rayuso@usgs.gov

For more information, detailed 

descriptions, and complete bibliographies on these and other 

project-related studies, please visit 

http://minerals.usgs.gov/east/humid/

index.html.

Levitan, D.M., Hammarstrom, J.M., 

Gunter, M.E., Seal, R.R., II, Chou, I.-M., 

and Piatak, N.M., 2009, Mineralogy 

of mine waste at the Vermont Asbestos Group mine, Belvidere Mountain, 

Vermont: American Mineralogist, v. 94, 

p. 1063–1066.

MacDonald, D.D., Ingersoll, C.G., and 

Berger, T.A., 2000, Development and 

evaluation of consensus-based sediment quality guidelines for freshwater 

ecosystems: Archives of Environmental 

Contamination and Toxicology, v. 39, 

no. 1, p. 20–31.

Piatak, N.M., Seal, R.R., II, Hammarstrom, J.M., Kiah, R.G., Deacon, J.R., 

Adams, Monique, Anthony, M.W., 

Briggs, P.H., and Jackson, J.C., 2006, 

Geochemical characterization of mine 

waste, mine drainage, and stream 

sediments at the Pike Hill copper mine 

Superfund site, Orange County, Vermont: U.S. Geological Survey Scientific Investigations Report 2006–5303, 

120 p., accessed October 15, 2009, at 

http://pubs.usgs.gov/sir/2006/5303/.

Piatak, N.M., Seal, R.R., II, Levitan, D.M., 

and Hammarstrom, J.M., 2009, Geochemistry of mine waste, mine drainage, 

and stream sediments from the Vermont 

Asbestos Group mine, northern Vermont, 

USA: International Conference on Acid 

Rock Drainage, 8th, Skellefteä, Sweden, 

June 23–26, 2009, [Proceedings], 10 p.

Seal, R.R., II, Hammarstrom, J.M., Johnson, A.N., Piatak, N.M., and Wandless, 

G.A., 2008, Environmental geochemistry of a Kuroko-type massive sulfide 

deposit at the abandoned Valzinco mine, 

Virginia, USA: Applied Geochemistry, 

v. 23, no. 2, p. 320–342.