Sulphur Isotopes Trace Elements and Mine

Water Air Soil Pollut (2008) 192:85–103
DOI 10.1007/s11270-008-9637-8

Sulphur Isotopes, Trace Elements and Mineral Stability
Diagrams of Waters from the Abandoned Fe–Cu Mines
of Libiola and Vigonzano (Northern Apennines, Italy)
Gianni Cortecci & Tiziano Boschetti &
Enrico Dinelli & Roberto Cabella

Received: 5 November 2007 / Accepted: 27 January 2008 / Published online: 17 February 2008
# Springer Science + Business Media B.V. 2008

Abstract The geochemical characteristics of rills
draining pyrite-chalcopyrite tailings impoundments
and of bordering streams were investigated at the
ophiolite-hosted Libiola and Vigonzano abandoned
massive sulphide mines, northern Apennines Italy.
G. Cortecci (*)
Istituto di Geoscienze e Georisorse,
Area della Ricerca-CNR,
Via Moruzzi 1,

I-56124 Pisa, Italy
e-mail: g.cortecci@igg.cnr.it
T. Boschetti
Dipartimento di Scienze della Terra, Università di Parma,
Viale Usberti 157a,
I-43100 Parma, Italy
E. Dinelli
Centro Interdipartimentale di Ricerca per le Scienze
Ambientali, Alma Mater Studiorum-Università di Bologna,
Centro di Ravenna, Via Sant’Alberto 163,
I-48100 Ravenna, Italy
E. Dinelli
Dipartimento di Scienze della Terra e Geologico-Ambientali,
Alma Mater Studiorum-Università di Bologna,
Piazza Porta San Donato1,
I-40126 Bologna, Italy
R. Cabella
Dipartimento per lo Studio del Territorio e delle sue Risorse,
Università di Genova,
Corso Europa 26,

I-16132 Genova, Italy

Water samples were analysed for major and trace
chemical composition, hydrogen and oxygen isotope
composition, and sulphur isotope composition of
aqueous sulphate. Sulphur isotope composition was
determined also for some samples of ore sulphides. At
Libiola, the newly acquired chemical results on
waters corroborate those from previous investigations,
thus providing additional support to existing geochemical models in terms of metal distribution, solid
phases precipitation, reaction path modelling and
mixing reaction paths, and environmental problems.
At Vigonzano, the chemical characteristics of waters
are similar to those at Libiola. In both localities,
solution-secondary phase equilibria estimated using
an updated thermodynamic dataset account for mineralogy in the field, including poorly crystalline
phases like jurbanite and hydrowoodwardite. The
hydrogen and oxygen isotope composition of waters
at Libiola and Vigonzano agrees with their meteoric
origin. Acid to neutral mine waters do not show any

significant isotope shift with respect to the initial
water, in spite of the oxidation of even large amounts
of pyrite/chalcopyrite ore. The sulphur isotope composition of aqueous sulphate in mine rills at Libiola
(δ34S=5.6 to 8.5‰; mean 6.5‰) matches that of
massive sulphide ore (δ34S=−0.5 to 6.7‰; mean
5.8‰), in keeping with the supergenic origin of the
sulphate and related isotope effects in the sulphide
oxidation process. Sulphate in mine waters at Vigonzano displays lower δ34S values in the range 0.6 to

86

1.5‰. The δ34S signature of massive ore specimens is
within the range reported for most volcanic-hosted
massive sulphide deposits, including Cyprus-type
deposits.
Keywords Apennine ophiolites . mine water .
sulphidic mine tailings . sulphur isotopes .
water isotopes

1 Introduction

Massive sulphide ore deposits have great potential
environmental concerns, which include human health
risks, ecosystem risks and physical hazards (Seal et al.
2002; Seal and Hammarstrom 2003). The ecosystem
risks are related to the acid mine drainage (AMD)
especially in abandoned mine sites. AMD is originated by the oxidation of sulphides, mostly pyrite, and
leads to the mobilization of metals. This process has
been recognized as a major environmental issue, and
geochemical, pollution, health and management
issues have been summarized in several important
reference works dealing with geoenvironmental models of mineral deposits or mine wastes (Alpers et al.
1994; Plumlee and Logsdon 1999; Filipek and
Plumlee 1999; Jambor et al. 2003; Lottermoser 2003).
The study sites are located in the northern
Apennines (Italy). In particular the Libiola mine is
located in the drainage basin of the Gromolo River,
about 8 km NE of the town of Sestri Levante on the
Ligurian Sea coast (Fig. 1). The ore deposit is
stratabound, and occurs in pillow lavas and pillow
breccias of the Internal Ligurides (Eastern Liguria

province) at the floor of the sedimentary cover (late
Jurassic-Cretaceous) (Ferrario and Garuti 1980, and
references therein). The lavas are partially overthrusted by serpentinites with local intercalations of
rodingitized gabbros. The deposit consists mostly of
massive lenses of pyrite and chalcopyrite (and minor
sphalerite) nearly concordant with the pillow layering.
Gangue minerals are scarce and include mainly
carbonates and some quartz (Bertolani 1952). Ore also
exists as disseminations (small aggregates) in pillows
and host volcanic breccia, and as stockwork discordant
with respect to the lava beds. No primary sulphate
minerals were identified in the deposit (Bertolani 1952;
Ferrario 1973). The presence in the ore of strongly
deformed and fractured chalcopyrite crystals testifies

Water Air Soil Pollut (2008) 192:85–103

for the Alpine tectonics undergone by the deposit
(Bertolani 1952).
A submarine hydrothermal origin was suggested

by Spooner et al. (1974) and Bonatti et al. (1976) for
all the three types of ore occurrences, whereas some
doubts were raised by Ferrario and Garuti (1980) for
the massive and disseminated ones which they
thought may be magmatic, that is closely related to
the volcanic products.
The economic exploitation of the Libiola mine
started in the XVII century and ended in 1965. The
mine tailings, located at 335 and 230 m a.s.l., extend
over about 0.5 km2 and are crossed by rills that
convey in the Gromolo, Rio Boeno and Rio Cattan
creeks (see Fig. 1). The latter two are tributaries of the
Gromolo creek.
Previous hydrochemical studies in the Libiola mine
area were carried out by Cortecci et al. (2001), Dinelli
et al. (2001) and Marini et al. (2003) on acid to near
neutral waters from the tailings and polluted and
unpolluted bordering stream waters. To be also
mentioned the geochemical modelling by Accornero
et al. (2005), who investigated the fate of major and

trace elements in acid water from the Libiola mine
after mixing with the Gromolo stream freshwater.
These papers deal with sampling campaigns carried
out in different seasons, i.e. November 1996, April
1997, May 1997, December 1997, May 1998,
October 1998 and May 2000. Additional water
samples from acidic discharges and the Gromolo
stream were analysed in July to October 2003 and
April 2004 (Accornero et al. 2005).
The ore deposit of the derelict Vigonzano mine is
located at 750–800 m a.s.l. in the vicinity of the
homonymous village in the Piacenza province (EmiliaRomagna region), about 30 km inland from the Libiola
mine, on the other side of the Apennine divide. As the
latter, it consists mostly of massive pyrite and
chalcopyrite, hosted within serpentinites and basalt
breccias (External Ligurides), at the boundary between
ophiolitic rocks and pelitic sediments (Dinelli et al.
1996, and references therein); it should be also related
to Jurassic-Cretaceous submarine volcanism, and then
underwent intense tectonic deformation during the

Alpine orogeny.
The mine tailings at Vigonzano cover a surface of
about 0.3 km2 and are crossed by rills, which convey
in the Vigonzano creek. Water sampling were carried
out in November 1997 from three sites along an

Water Air Soil Pollut (2008) 192:85–103

87

Fig. 1 The Libiola and
Vigonzano mine tailings
impoundments within the
Apennine context and sampling location of selected
stream and mine waters (see
Tables 2, 3 and 4). Water
samples were analysed for
chemical and isotopic (H, O
and S) compositions (complete), for chemical and
isotopic (H and O; no S

isotopes) compositions, or
only for chemical composition (no isotopes)

ephemeral rill issuing from an elevated exploratory
pit, and in June 1998 from only the uppermost site fed
by a quite small water flow. In June 1998, a blue
deposit was observed along the uppermost part of the
rill. The Rio Vigonzano was also sampled just
downstream of the rill both in November 1997 and
June 1998.
In the present work, water samples (Libiola:
December 1997, May and October 1998; Vigonzano:

November 1997, June 1998) were analysed for major
and trace chemical elements, and for hydrogen and
oxygen isotopes of water and sulphur isotopes of
dissolved sulphate (Libiola: December 1997; Vigonzano: Novembre 1997). In addition, ore samples and
vein sulphides in the rocks were also analysed for the
sulphur isotope composition. The present work was
aimed to (1) complement the extended abstract by

Cortecci et al. (2001) on the Libiola mine with a more

88

complete presentation and a deeper discussion of the
isotopic data dealing with water and ore samples, (2)
integrate and extend geochemical modelling of acid
mine waters and their evolution, (3) compare the
original data on the Vigonzano mine with those on
the Libiola mine, the ore deposits being nearly
coeval and both hosted in basalts, (4) use the
hydrogen and oxygen isotopes of water as natural
tracers of hydrologic processes in acid mine drainage
systems, (5) verify the sulphur isotope fractionation
involved in the sulphide mineral supergenic oxidation, and (6) provide constraints on the origin of the
ore deposits.

2 Previous Studies
Waters from the Libiola mine tailings include acid
terms from oxidative drainage of pyrite and chalcopyrite ore. These waters are “red” in the most acidic

sites (pH 2.4–2.8), and their colour is due to very fine
suspended Fe-particulate. They are oversaturated with
respect to jurbanite and close to saturation with
respect to ferrihydrite (Marini et al. 2003). The red
waters neutralize to “blue” waters (pH 6.5–7.5)
through water–rock interaction (Dinelli et al. 2001),
reaching saturation/oversaturation with respect to
gibbsite and basaluminite, and saturation relative to
antlerite, brochantite and alunite. Both red and blue
waters are slightly undersaturated with respect to
gypsum (Marini et al. 2003). However, identified
minerals in red waters were amorphous silica, Fe(III)oxhydroxides, schwertmannite and jarosite (Dinelli
et al. 1998; Derron 1999; Dinelli and Tateo 2002),
and probably basaluminite, gibbsite and a Cu-Al
sulphate hydrate (azure-blue coloured) are the precipitates in blue waters (Derron 1999). Depending on the
water discharge, the sediments may change seasonally
their colour. In these cases, the water-sediment pairs
are located at higher elevation in the mine area and
are affected by considerable fluctuations of the water
table. The colour of sediments was found to change
from ochre (Fe-rich) to blue-green (Cu-rich), following a pH variation of the water from acid to near
neutral (Dinelli and Tateo 2002).
Red waters issue from exploratory pits located in
the bottom of the Gromolo River valley (Ida and
Castagna tunnels, at 106 and 72 m a.s.l., respectively), whereas blue waters are discharged by a higher

Water Air Soil Pollut (2008) 192:85–103

tunnel near to the Rio Cattan stream (Margherita
tunnel; 209 m a.s.l.), a tributary of the Gromolo River.
All these sites display a rather constant water flow
rate over the year, testifying that the discharge point
is close to the intersection of the water table with the
topographic surface (Dinelli et al. 2001), and the
sediments maintain their colour all over the year.
According to Marini et al. (2003), the main process
governing the chemical composition of all the mine
waters of Libiola (red, blue and intermediate) is their
interaction to variable extents with the waste material.
Mixing between acid mine waters (red to orange) and
local groundwater should be insignificant, that is all
mine waters at Libiola derive from the interaction of
percolating meteoric water with mine tailings or with
ore.
In both red and blue waters, sulphate is the
dominant anion; calcium and magnesium are the
main cations, reflecting the acid alteration of local
rocks (Dinelli et al. 2001; Marini et al. 2003). Mg is
particularly rich in the acid waters, which greatly alter
the mafic silicates present in the tailings and country
rocks. At times, iron is the prevailing cation in the red
water, due to an appropriate combination of ore
oxidation and pH of solution (Dinelli et al. 2001).
Finally, red waters are richer in metals (Al, Fe, Cu, Zn
and Mn) than blue waters.
Water from the Gromolo River and Rio Boeno
upstream of the mined area is Mg (± Ca)-HCO3 and
comparatively very diluted for both major and trace
constituents (Dinelli et al. 2001; Marini et al. 2003).
The chemical composition of these surface waters
match that of spring water issuing from serpentinites
in Liguria and Emilia Romagna regions, its chemical
composition varying from Ca-HCO3 to Mg-HCO3 to
Ca–(Na)–OH (Bruni et al. 2002; Boschetti and
Toscani 2008).
At Vigonzano, previous studies dealt with the
geochemical characterization of the waste rock piles
from the mining works (Dinelli et al. 1996), the
transfer of metals to vegetation (Dinelli and Lombini
1996) and the element mobility in the surrounding
area (Dinelli and Tateo 2001a, b) with particular
reference to the role played by fine-grained authigenic
particulate (Dinelli et al. 1998). Some data on surface
waters (Dinelli and Tateo 2001a) indicate that there is
acidic water circulation, just limited to the mine waste
area and not affecting consistently the metal chemistry of stream waters.

Water Air Soil Pollut (2008) 192:85–103

89

3 Sampling and Methods
The sampling sites at Libiola in December 1997 to
October 1998 are shown in Fig. 1. Water samples
were collected from rills draining the waste dumps

and the streams bordering the mining area (Gromolo
River and Rio Boeno). Temperature, pH, Eh, EC and
alkalinity were measured in the field. Water was
filtered through 0.45 μm membranes of cellulose
acetate, and portions stored for analyses. The portion

Table 1 Thermodynamic data of aqueous species and mineral phases added to the thermo.com.V8.R6 dataset
Aqueous species and
mineral phases

ΔG0f kJ=mol ΔH0f kJ=mol LogKa
(25°C)

logKa
(0°C)

Reference

AlðOHÞ4
AlðSO4 Þ2
AlSOþ
4
Al2 ðOHÞ4þ
2
AlðOHÞ03
Al13 O4 ðOHÞ7þ
24
Al3 ðOHÞ5þ
4
CuSO04
CuOH+

–
–

–
–

–
–
–
–
−691.76
−126.16

–
–
–
–
−838.81
–

−22.1567
−4.9029
−3.0096
7.67
16.17
98.71
13.86
−2.3607
7.9500

−25.4631
−4.7131
−2.9442
9
18.44
125.19
17.64
−2.2789
–

CuHCOþ
3
CuðOHÞ02

−535.45
−315.75

–
–

−2.41
16.30

–
–

Cu2 ðOHÞ2þ
2

−248.06

–

10.36

–

thermo.dat
thermo.dat
thermo.dat
thermo.dat
thermo.dat
thermo.dat
thermo.dat
Vieillard 1988
Vieillard 1988;
Powell et al. 2007
Vieillard 1988
Vielliard 1988;
Powell et al. 2007
Vieillard 1988

Antlerite
–
Bayerite
Basaluminite

Cu3SO4(OH)4(H2O)2
Cu3SO4(OH)4
Al(OH)3 amorphous
α–Al(OH)3
Al4(OH)10SO4

−1919.6
−1445.0
−1137.63
−1149.8
−4937.199b

−2303.8
−1726.7
−1285.04
−1282.71
−5516.73

8.9718
9.0130
10.78
8.6497
22.7

10.9561
11.0842
12.5599
10.4647
29.1909

Bonattite

CuSO4(H2O)3

−1399.36

−1675.73

−1.67

−1.42

Copiapite
Coquimbite
–
Ferricopiapite
Halotrichite
Hydrowoodwardite

Fe5(SO4)6(OH)2(H2O)20
Fe1.47Al0.53(SO4)3(H2O)9.65
Fe2(SO4)3(H2O)5.03
Fe4.78(SO4)6(OH)2.34(H2O)20.71
FeAl2(SO4)4(H2O)22
Cu0.83Al0.17(OH)2(SO4)0.085
(H2O)1.1
Al(OH)SO4
MgAl2(SO4)4(H2O)22
(H3O)Fe(SO4)2(H2O)3
Fe8O8(OH)4.4(SO4)1.8
FeSO4(H2O)5
Cu(OH)2

−1510.75
−9971
−3499.7
−3499.7
−9036.9
−786.91

−5738.4
−11824
−4115.8
−4115.8
−11041
−951.64

−22.04
−6.94
−6.8
−12.89
−8.13
7.0252

−18.63
−4.4
−4.4
−9.08
−7.25
7.8073

Pollard et al. 1992
Pollard et al. 1992
wateq4f.dat
Verdes et al. 1992
wateq4f.dat; Singh
1980; this study
Vieillard 1988;
Chou et al. 2002
Hemingway et al. 2002
Majzlan et al. 2006
Majzlan et al. 2006
Majzlan et al. 2006
Hemingway et al. 2002
this work

−1487.692 b
−9674.88
−2688
−4378.07 b
−2033.9
−359.35

−1635.22
–
−3201.1
−5052.85
−2424.3
−443.10

−3.23
−8.73
−2.05
7.17
−2.11
8.66

−1.6489
–
−0.76
16.05
−2
9.6697

wateq4f.dat; this study
Reardon 1988
Majzlan et al. 2006
Accornero et al. 2005
Hemingway et al. 2002
Vieillard 1988

Aqueous species

Mineral phases

Jurbanite
Pickeringite
Rhomboclase
Schwertmannite
Siderotil
Spertiniite

Last version of the original thermo.com.V8.R6 and thermo.dat files are available in Hydrogeology Program, Department of Geology,
University of Illinois (retrieved January 11, 2008, from http://www.geology.uiuc.edu/Hydrogeology/hydro_thermo.htm). See text for
details
a

Note that in phreeqc’s datasets the solution species are in the right side of reaction, therefore the sign must be inverted.

b

Calculated from logK(25°C).

90

Water Air Soil Pollut (2008) 192:85–103

for determination of metals was added with suprapure
HNO3. Within a few days after collection, all water
samples were analysed for Cl (Idrimetric-Kits by
Carlo Erba), SO4 (turbidimetry/spectrophotometry;
HACH reagent and instrument), Na, K, Ca, Mg, Fe,
and Mn (AAS), Zn, Cu, Cd, Co, Ni, Cr, Ba and Pb
(GF-AAS), and Al (turbidimetry/spectrophotometry;
HACH reagent and instrument). Precisions were of 3
to 5% for major elements and 5–10% for minor and
trace elements. Detection limits were: 1 μg/L for Cd
and Pb, 2 μ/L for Cu, Zn, Cr and Ba, 5 μg/L for Ni
and Co, and 10 μg/L for Al, Fe and Mn. In the
colourless waters at Libiola (see Table 3), Cr and Cd
were determined after preconcentration by solvent
extraction technique (Danielsonn et al. 1978).

Aqueous sulphate for the sulphur isotope analysis
was separated as BaSO4, which was thermally decomposed to SO3, and then reduced to SO2 for the
spectrometric measurement, using a method similar to
that of Holt and Engelkemeir (1970). Ore samples
were checked for main mineralogy by XRD. Total ore
samples and mineral separates were analysed, the latter
being not pure phases, but mixtures in variable
proportions of pyrite and chalcopyrite (± sphalerite).
Before combustion in a stream of pure oxygen to
produce SO2 for the mass spectrometric analysis
(Thode et al. 1961), ore samples were treated with
diluted HCl in an ultrasonic bath to remove alteration
products, carbonates and oxides. The results are
reported in δ34S unit, in per mil, relative to the CDT

Table 2 Chemical and isotopic composition data on coloured waters from the mine tailings at Libiola
Sampling site

Colour
T°C
pH
EC (μS/cm)
Eh (mV)
HCO3 (mg/L)
Cl
SO4
Na
K
Ca
Mg
Fe
Zn
Cu
Al
Mn
Cd (μg/L)
Ni
Co
Pb
Ba
Cr
δ34S(SO4)
δ18O(H2O)
δ2H(H2O)

18 (1)

18 (2)

18 (3)

22 (2)

22 (3)

16 (1)

16 (2)

16 (3)

17 (1)

17 (2)

17 (3)

Red
12
2.5
7670
466
nd
nd
5100
24.9
1.4
340.2
306
891
34
221
265
9.9
130
6400
4140
7