OUTOKUMPU-TYPE ORES

Geological Survey
of Finland,
Special Paper
I
Outokumpu-type ores
OUTOKUMPU-TYPE ORES
by
Heikki Papunen
Papunen, Heikki, 19E7. Outokumpu - type ores. Ceological Survey of
Finland, Special Paper 1.41-50, ll figures.
The Outokumpu ore type includes both massive Cu-Zn-Co and
disseminated Ni sulphide deposits. The ores are associated with a rock
assemblage of serpentinites, calc-silicate rocks, cherty quartzites and
black schists embedded in sedimentogeneous mica gneisses. The Outokumpu Cu-Zn-Co deposit is predominantly pyritic whereas the others
are predominantly pyrrhotitic. The ores primarily deposited by seafloor
hydrothermal processes but were deformed by a thrust which upgraded
the primarily thin bed into thick massive plates. The exceptional
mineralogical and chemical compositions
with abundant
of metamorphism in middle amphibolite
a hydrothermal deposit associated with ultramafics.
silicates are the result
chrome
facies of
Key words: metal ores, sulphides, classification, genesis, hydrothermal
process, metamorphic rocks, Proterozoic, review, Outokumpu, Finland.
Heikki Papunen, Department o.f Geology University
of Turku,
SF-
20500 Turku. Finland
INTRODUCTION
During the past decades of mining in Outokumpu a number of ideas have been presented
concerning the origin and type of the outokumpu ore. These ideas reflect not only the progress
made in direct observations at the mines but
also changes in general ore geological conceptions in different periods. Based on the epigenetic
character noted in the contact relations of the
ore, early models took various intrusive rocks,
such as the Maarianvaara granite (Trüstedt
l92l\, serpentinite (Mäkinen 1921) and a nonoutcropping felsic intrusive rock (Eskola 1933,
Väyrynen 1939 and Vähätalo 1953) as the par-
ent rocks of the ore. Selective tectonic mobilization of the black schist sulphides was proposed
by Saksela (1957). Basing his conclusions on the
extensive descriptions by Vähätalo (1953) and
Disler (1953), Borchert was the first author to
propose a volcanic exhalative origin for the ore.
His idea was later supported and modified by
M. Mäkelä (1974), Gaäl et al. (1975), Peltola
(1978), K. Mäkelä (1981), Koistinen (1981),
Bowes et al. (1984) and Parkkinen and Reino
(1985). The present paper is a review of the
geology and classification of the Outokumpu
ore deposits.
4l
Geological Survey
of Finland,
I Heikki
Special Paper
Papunen
:
za:lso'
Ir
l
V
I
I
i
rl\\
,l.\
\t\
t.\
(u
NKAAVI
KA
.t
t
\rn
\)\
I
,,b "'THKAL/'
HTI
63
I
rx.
\
"\/
-z/t
/
MAARIANVAARA
I
\_.4:,
t/
t/.t,,,,7 t
VUONOS
I
?tt
'w
+\
^/i
SO
\ü
MA\TI
\r\
KERETTI 9
'<:
VIJARVI
I
-Y"'&
>:
R | | l{ l-r
^* tt
LAHTI
,1'-72,
o'
14.
.
SVECOKARELIAN ROCKS
(Proterozoic
rJ;l
I /-
-
)
GRANITE
MrcA scHrsr/
swE DEru
VEINED GNEISS
-: I BLACK
)rrl,.r.o*J( ussR
SCHIST
AND
Ear SERPENTINITE
ASSoctATED RocKS
lW-t BASIC IGNEOUS ROCK
r....:1 euARTztTE
I cu-ore or -showing
,a mine, quarry
Garnet
s illiman ite
--< cordrerite
< staurolite
PRESVECOKARELIAN BASEMENT
( Archaean
reFig.
42
l.
)
GRANtTOIDS, AUGEN
,\v anthophyllite,
cummingtonite
O andalusite
kyanite
Geological map of the Outokumpu region; according to Koistinen (1981) and Parkkinen and Reino (1935).
Geological Survey
of Finland, Special Paper I Outokumpu-type
ores
GENERAL CHARACTERISTICS OF THE ROCK TYPES
of the Outokumpu region has
Serpentinites have been formed from dunites,
been extensively studied in exploration peridotites and pyroxenites (Haapala 1936).
The geology
conducted by Outokumpu Oy during the last
three decades (e.g. Huhma 1975 and 1976,
Huhma and Huhma 1970, Gaäl et al. 1975 and
Koistinen l98l) (Fig. l). According to available
information, the copper ores of the Outokumpu
region are related to a rock association of
serpentinites, dolomites, calc-silicate rocks,
cherty quartzites and black schists, listed from
the serpentinite core outwards. The rock assemblage has been called the Outokumpu
Association and it meanders as a discontinuous
band for up to 250 km in the Karelian metasediments. The largest lenticular serpentinite bodies
may be as much as l0 km long and 500 m thick.
Wherever the heterogeneous dolomite-skarnquartzite envelope of the serpentinite bodies is
isoclinally folded between tongues of serpentinite it varies in thickness from a few metres to
c. 100 metres. The most continuous rock types
are the black schist horizons, which mark the
extension of the Association even it the serpen-
tinites are lacking. Middle amphibolite facies
metamorphism changed the mineral composi-
tion, and minerals such as
cordierite,
anthophyllite, staurolite, andalusite, kyanite
and sillimanite indicate the highest P-T conditions of metamorphism (Treloar et al. 1981).
Unaltered pyroxenites have also been detected
in places. Besides serpentinization, carbonation
has locally altered the margins of the serpentinite bodies into talc-carbonate rocks, which
have been mined as a talc ore at three sites in
Polvijärvi. Metamorphic olivine exists in serpentinite and dolomite as long blades resulting in a
texture called "ophidolomite". (Fig. 2).
At Horsmanaho, northwest of Outokumpu, a
coarse-grained amphibole (-pyroxene) gabbro is
encountered among serpentinite (Koistinen
l98l). In places banded amphibolites ("barren
skarns") and chlorite schists with dark amphibolites probably represent metamorphosed
mafic volcanics (Park and Bowes L982). However, their abundances are small compared with
those of serpentinites and their common envelopes.
A zone of dolomite often occurs adjacent to
serpentinite, and close to talcose ultramafics in
particular. Chrome diopside or chrome
tremolite skarn (calc-silicate rock) is an intermediate member between ultramafics and quartzites where dolomite is absent. Banded skarn
quartzite represents gradation to quartzite.
Quartzite containing layers of dolomite,
skarn minerals, carbonaceous material and sul-
Fig. 2. Serpentine pseudomorphs after metamorphic olivine in dolomitic host rock ("Ophidolomite").
43
Geological Survey
of Finland,
Special Paper
1 HeiAki Papunen
phides is the banded metamorphic equivalent
of
the original chert horizon (Huhma & Huhma
1970, Huhma 1976). The colour of the quartzite
depends on the accessory minerals, pure quartzite being white, the sulphide-bearing and carbonaceous varieties dark and the chrome
silicate-bearing variety green (Fig. 8); chromite
imparts a brownish hue.
Calcareous, argillaceous and quartz-rich varieties of black schists are associated with the
serpentinite-quartzite assemblage (Peltola 1960'
1968). The amount of carbonaceous material is
between I and 30 90, with 5 9o as an average.
The content of sulphides, pyrite, pyrrhotite,
chalcopyrite and sphalerite varies in line with
the carbon content. The contacts of the black
Assemblage is the abundance
of a wide variety
of chrome-bearing minerals in all the enveloping
rock types (Eskola 1933). The calc-silicate rocks
are green owing to chrome diopside, chrome
tremolite and uvarovite (Figs. 3 and 8). Fuchsite
and chromite are common accessories in the
quartzite; other chrome silicates are kaemmererite, tawmawite (chrome epidote) and chrome
tourmaline. The chromite of the Association is
zinc-rich (up to 9.6 0/o Zn) and also vanadiumbearing up to 3 9o V) (Thayer et al. 1964,
Weiser 1967). Straurolite and garnet also
contain zinc exceptionally (0.40-0.87 Vo Zn in
staurolite and 0.62 s/o Zn in garnet; Treloar et
al. l98l).
schists against quartzite are sharp, whereas
there is gradation from black schists to mica
Granite and pegmatite veins, originating from
the nearby Maarianvaara granite, intersect the
rocks of the Outokumpu Assemblage and the
gneiss.
orebodies.
A
characteristic feature
Fig.
3.
of the Outokumpu
Uvarovite crvstals
in chrome-bearins calc-silicate
rock.
THE ORES
The Outokumpu Cu-Zn-Co deposit is the
largest of several sulphide deposits related to the
Outokumpu Assemblage. The deposit is alternatively known as the Keretti ore deposit,
after the Keretti mine currently being in operation at the SW end of the Outokumpu ore
deposit. The other mineable deposits are Vuo44
nos, c. 6 km NE of Outokumpu, and Luikonlahti, c. 30 km NW of Outokumpu (Fig. l).
Miihkali, Sola and Hietajärvi are minor deposits closely related to Vuonos. The Riihilahti
orebody, which is associated with cumming-
tonite rocks, garnet-bearing
gneisses and
calc-silicate rocks enveloping the ultramafic
Geological Survey
bodies in the mica gneiss host rock differs in its
rock association from the typical ores of the
Outokumpu Assemblage (Merkle 1982).
The Outokumpu Cu orebody is lens shaped,
c. 4 000 m long, 250 to 300 m wide and usually
less than 10 m thick, but it may attain a
thickness of 30-40 m. The ore averages 3.80 9o
Cu, 1.00 9o Zn, 0.24 Vo Co, O.l2 o/o Ni,
28.10 9o Fe and 25.30 Vo S; the tenors of minor
elements are 0.8 g/t Au, 9 g/t A9,25-50 ppm
Se; 0.015 9o V20r, 0.015 9o Sn and 0.005 9o Pb.
The Keretti ore contained c. I x 106 tonnes of
copper metal. The ruler-shaped Vuonos ore-
of Finland, Special Paper I Outokumpu-type
ores
body is ca. 3 500 m long, 50-200 m wide and
an average of 5 to 6 m thick. Characteristic
average tenors of metals are2.l8 Vo Cu, 1.38 9o
Zn,0.l3 9o Co, 0.12 Vo Ni, 14.76 9o S, l0 ppm
Ag and l2 ppm Se. The ore types of Luikonlahti are similar to those of Vuonos, but the rock
assemblage and ores are more deformed and
intersected by numerous granitic veins, and the
copper ore occurs in several separate subvertical
lenses. In 1968-1983 three orebodies totalling
c. 7.7 mill. t of ore were exploited. The average
metal values were l.2Vo Cu, 0.l2Vo Co,
0.09 9o Ni, 0.65 Vo Zn and 20 9o S.
ORE TYPES
Sulphides occur in the Outokumpu Assemblage as two main ore types: 1) massive Ctt-ZnCo-Fe- ores and 2) stringe-disseminated Ni-rich
sulphides. In the massive ore the nickel to
cobalt radio averages l:2, but drops as low as
1:5 in the centre of the Keretti orebody. In the
nickel occurrence the corresponding ration averages c. 10 (Parkkinen and Reino 1985).
The host rock of the copper ore is quartzite.
The contacts are sharp and well defined (Figs. 6
and 9), but a low-grade quartz-rich marginal
zone is common (Fig. 5). Structurally the ore
can be divided into layered (Fig. 4) and brecciated (Fig. 7) types, the latter representing
mobilized sulphides from the polyphase defor-
mation period (Koistinen 1981).
The massive ores contain over 50 9o sulphide
minerals, and quartz is almost the only gangue
mineral. Mineralogically the massive ore can be
divided into pyrite and pyrrhotite types. The
large Outokumpu orebody is mainly of the
pyrite type whereas Vuonos, Luikonlahti and
some minor occurrences are predominantly of
the pyrrhotite type. In addition to iron sulphides, the main ore minerals are chalcopyrite
and sphalerite. Pyrrhotite is a non-magnetic
hexagonal variety but locally also troilitic.
Cobalt pentlandite is the main carrier of cobalt
in the pyrrhotitic ore types whereas cobalt is
included in pyrite in the pyritic ore type, and the
coexisting pentlandite is poor in cobalt.
Cubanite is a common constituent of mobilized
Cu-rich ores. Common accessory minerals are
stannite, cobaltite, zincian chromite
and
pentlandite
magnetite. In addition to cobalt
(Kouvo et al. 1959), the Keretti oreboby is a
type locality for several ore minerals: eskolaite
(Kouvo and Vuorelainen 1958), mackinawite,
which was first described here as "tetragonal
iron sulphide" (Kouvo et al. 1963), karelianite
(Long et al. 1963) and argentian pentlandite
(Vuorelainen et al. 1972).
Nickel-rich sulphides exist as dissemination
and stringers in quartzite and calc-silicate rocks
between serpentinite and mica schist (Parkkinen
and Reino 1985). The nickel occurrences are
spatially associated with massive copper ores
(Fig. l0). In Vuonos the nickel occurence
extends as a steeply dipping horizon from the
upper edge of the copper ore up to the surface.
It was mined in the early 1970s from an open pit
as low-grade nickel ore. A similar deposit lies
parallel to the Keretti copper orebody.
The host rocks of the nickel occurrence are
quartzite, skarn and chlorite schist, but the
occurrence includes a network of mica rock
which is abnormally rich in Mg, Fe and Al and
poor in Ca. It contains cordierite, phlogopite,
chlorite, muscovite, almandine, cummingtonite
and plagioclase.
The sulphide mineral assemblage includes
pyrrhotite, pentlandite, chalcopyrite and sphalerite; pyrite exists locally, but the sulphide
phase is then poor in nickel. Pentlandite, the
main carrier of nickel, contains an average of
31.5 9o Ni and 3-14 Vo Co, the average
content being 3.8 90. The pentlandite of the
massive copper ore averages 17 Vo Ni and 33 9o
Co. According to Parkkinen and Reino (1985),
the quartzite-skarn horizon hosting the nickel
occurrences and copper ore has elevated Cu, Ni,
Co and Zn values along its whole length.
Likewise the tenor of chromium is highest in the
rocks containing anomalously high nickel
values.
45
Geological Survey
of Finland,
Special Paper
I Hei6ki Papunen
Fig. 4. Layered ore type, the Keretti mine.
Intensely folded disseminated ore; "the Baby orebody", the Keretti mine.
46
Geological Survey
Fig. 6. Mobilized massive ore, Keretti. Scale bar l0 cm.
Fig. 8. Green, chrome-bearing skarn bands in quartzite;
the white vein is mobilized quartz. Scale bar 20 cm.
of Finland, Special paper I Outokumpu-type
Fig. 7. Folded and brecciated quartzite layer in
ore, the Keretti mine; scale bar 20 cm.
Fig. 9. Hanging wall contact
quartzite; scale bar 20 cm.
of the
ores
massive
massive ore with
47
Geological Survey
of Finland,
Special Paper
I
HeikAi Papunen
IS OUTOKUMPU A UNIQUE ORE TYPE?
Current interpretations
of the origin of the
Outokumpu Association are based on
long-term, detailed geological, structural and
petrographical analyses (Mäkelä 1974, Gaäl et
al. 1915, Peltola 1978, Koistinen 1981, Bowes et
al. 1984, Parkkinen and Reino 1985). The Outokumpu Association consists of ultramafic
material from the mantle, which erupted about
2 100 Ma ago onto the bottom of a geosyncline,
probably a back arc basin (Bowes et al. 1984),
and then intruded along the trench axis close to
the bottom of the sea; some of the igneous
material extruded onto the sea floor (Park and
Bowes 1982). The heat flow associated with
igneous activity resulted in hydrothermal processes on the sea floor. as a result of which the
mantle-derived ultramafite became hydrated
and carbonated. Carbonate deposits and cherts
precipitated from the hot hydrothermal fluids
onto the ultramafites erupted onto the sea floor.
Simultaneously sulphides were also deposited
among the cherts (Fig. l1). The sedimentary
layering of the sulphides (see Figs. 4 and 5)
proves that they deposited from heavy saline
solutions resembling those in the present-day
Red Sea deposits. The heavy solutions accumulated in the basins along the trench axis on
the sea floor, and because of the topography of
the floor the Keretti and Vuonos orebodies
formed as independent occurrences. The hydrothermal activity caused by the igneous processes
raised and led to increased biogenetic activity,
of which the existence of black schists is a sign
(K. Mäkelä 1981). The isotopic composition of
the ore lead indicates a mantle origin if the
plumbotectonics model is applied (see Simonen
et al. 1978).
On account of the thrust that took place some
time after the ore deposited on the sea floor, the
ultramafites and the whole Outokumpu
Association, including the overlying metasediments, were displaced into their current position. At the same time polyphase deformation
piled the primarily thin sulphide deposits into
the present thick plates.
The separation of copper and cobalt sulphides from nickel sulphides to form zoning is
48
common to all massive sulphide ores and is due
to the variation in temperature under primary
hydrothermal conditions. It is typical of the
Outokumpu area that chromium participated in
the hydrothermal process. This distinguishes the
hydrothermal convection in an ultramafic
environment from that on the present-day sea
floor, which takes place in mafic igneous rocks.
Chromium followed nickel in the hydrothermal
process. The very low lead concentration is
characteristic of all occurrences of the ophiolite
(Cyprus) type setting.
The rocks of the Outokumpu Association
were metamorphosed while undergoing deformation, and the present peculiar mineral composition with chromium-bearing silicates and
many rare ore minerals is due to recrystallization under conditions of the amphibolite facies.
The Outokumpu ore has many features in
common with the Cu-Zn-Au occurrences of the
Cyprus type, which is associated with ophiolites, and with the Besshi type, which is associated with submarine mafic volcanites and sediments.
The specific characteristics of the Outokumpu
type of ore are:
high proportions
-
-
of ultramafites in the
Association
low proportion of demonstratably lava rocks
in the Association
hydrothermal alterations and chemical sediments
marked concentration of chromium in the
chemical sediments
low tenor of lead
separation of the Cu-Co-Zn and Ni mineralizations from each other
metamorphism; metamorphic mineral asof middle amphibolite facies
polyphase deformation, resulting in piling
- and mobilization of the ore.
Even if the Outokumpu ore cannot be considered a unique type it nevertheless has so
many special features that there is good reason
for classifying it as a subtype of the sulphide
ores associated with seafloor mafic and ultramafic volcanism.
-
semblages
Geological Survey
of Finland, Special Paper 1 Outokumpu-type
ores
+200
m
Ni:0.3%
Co > 0.03 %
0M50
I
m
ffi
Cu-ORE
ANOMALOUS ZONE
SERPENTINITE , TAtC ROCK,
DOLOMITE ROCK
QUARTZITE, SKARN
Cu
) 0.05 %
m
at'
MICA
SCH IST
,
BLACK SCH I5T
DRILT HOLE
Fig. 10. Distribution of Ni, Co and Cu in the profile y 193.750 of the Vuonos
deposit (from Parkkinen and Reino 1985).
PYROXENITE
Fig.
I 1.
A model of the palaeoenvironment during the deposition of Outokumpu-type
ores on the seafloor.
49
Geological Survey
of Finland, Special Paper I Heikki
Papilnen
REFERENCES
Borchert, H., 1954. Kritische Anmerkungen zu zwei neuen
Arbeiten über Outokumpu, Finnland. Chemie der Erde
17, l-5. (Zeitschrift für Erzbergbau und Metallhütten-
7, 82-4.'t
Bowes, D.R., Holden, N.M., Koistinen, T.J. & Park,
A.F., 1984. Structural features of basement and cover
rocks in the eastern Svecokarelides. Finland. 1n A.
Kröner and R. Greiling (eds.) Precambrian Tectonics
wesen
Illustrated E. Schweizerbart'sche Verlangsbuchhandlung Stuttgart" 147-171.
Disler, J., 1953. Die Kupferkieslagerstätte von Outokumpu, Finnland. Bull. Comm. 96ol. Finlande 16l, 108 p.
Eskola, P., 1933. On the chrome minerals of Outokumpu.
Bull. Comm. 96ol. F-inlande 103, 26-44.
Gaä|, G., Koistinen, T. & Mattila, E., 1975. Tectonics and
stratigraphy of the vicinity of Outokumpu, North
Karelia, Finland. Geol. Survey Finland, Blll.271, 67 p.
Haapala, P., 1936. On serpentinite rocks in Northern
Karelia. Bull. Comm. göol. Finlande I14, 80 p.
Huhma, A., 1975. Geological map of Finland l:100 000,
sheets 4222, 4224, 4311. Explanation to the map,
English summary. Precambrian rocks of the Outokumpu, Polvijärvi and Sivakkavaara map sheet areas. Geol.
Surv. Finland, l5l p.
Huhma,
1976. New aspects to the geology of the
^., region. Bull. Geol. Soc. Finland 48, 5-24.
Outokumpu
Huhma, A. & Huhma, M., 1970. Contribution to the
geology and geochernistry of the Outokumpu region.
Bull. Geol. Soc. Finland 42, 57-88.
Koistinen,
T.,
1981. Structural evolution
of an
early
Proterozoic strata-bound Cu-Co-Zn deposit, Outokumpu, Finland. Trans. Roy. Soc. Edinburgh; Earth Sci 72,
l5-158.
Kouvo, O. & Vuorelainen, Y., 195E. Eskolaite, a new
chromium mineral. Am. Mineral. 43. 1098-1106.
Kouvo, O., Huhma, M. & Vuorelainen. Y., 1959. A
natural cobalt analogue of pentlandite. Am. Mineral.
44. 897-900.
Kouvo, O., Vuorelainen, Y. & Long, J.V.P., 1963. A
tetragonal iron sulfide. Am. Mineral . 48. 5ll-524.
Long, J.V.P., Vuorelainen, Y, & Kouvo, O., 1963. Karelianite, a new vanadium mineral. Am. Mineral. 48.
33-41.
Mäkelä, K., 1981. On the potential of finding Outokumputype ore deposits in East- and North-Finland (English
summary), Geologi 33, 20-22.
Mäkelä, M,, 1974. A study of sulfur isotope in the
I
Outokumpu ore deposit, Finland. Geol. Survey Finland,
Bull. 267, 45 p.
Mäkinen, E., 1921. Over geologin inom Outokumpu
omrädet. Medd. Geol. Fören. Helsingfors 1919-1920,
l0-
50
I
7.
R., 1982. Geochemische Untersuchungen zur
Genese des Erzvorkommens Riihilahti,zFinnland. Dis-
Merkle,
sertation
an der
Johannes-Gutenberg-Universität
Mainz. 304 p.
Park, A.F. & Bowes, D.R., 19E2. Metamorphosed and
deformed pillows from Losomäki: evidence of subaqueous volcanism in the Outokumpu association, east-
ern Bull. Finland. Geol. Soc. Finland 54.
Parkkinen, J, & Reino, J., 1985. Nickel occurrences of the
Outokumpu type at Vuonos and Keretti. Geol. Survey
Finland. Bull. 333. 178-188.
Peltola, E., 1960. On the black-schists in the Outokumpu
region in Eastern Finland. Bull. Comm. göol. Finlande
t92, t01 p.
Peltola, E., 196E. On some geochemical features in the
black schists of the Outokumpu area, Finland. Geol.
Soc. Finland, Bull. 40, 39-50.
Peltola, E., 1978. Origin of Precambrian copper sulfides
of the Outokumpu District, Finland. Econ. Ceology 73,
461-4',77.
M., 1957. Die Entstehung der Outokumpu-Erze
im Lichte der tektonisch-metamorphen Stoff-mobilisier-
Saksela,
ung.Neues Jahrbuch der Mineralogie; Abh.91,
278-302.
4., Helovuori, 0. & Kouvo, O., 1978. Laatokan-Perämeren vyöhykkeen kallioperän erikoispiirSimonen,
ja iästä. In Laatokan Perämeren malmivyöhyke,
Symposium 1978. 02.16, Otaniemi, Vuorimiesyhdistys
teistä
ry. l0-19.
Thayer, T.P., Milton, C,, Dinnin, J, & Rose, H., 1964.
Zincian chromite from Outokumpu, Finland. Am. Min-
eral, 49, I178-1183.
Treloar, P,J., Koistinen, T.J. & Bowes. D.R.. 1981.
Metamorphic development of cordierite-amphibole
rocks and mica schists in the vicinity of the Outokumpu
ore deposit, Finland. Trans. Roy. Soc. Edinburgh Earth
Sci 72. 201-215.
O., 1921. Över geologin inom Outokumpu
omrädet, diskussion. Medd. Geol. Fören. Helsinefors
Trüstedt,
t9r9-t920,
16.
Vähätalo, V., 1953. On the geology of the Outokumpu ore
deposit
in Finland. Bull. Comm. 96ol. Finlande 164,
98 p.
H., 1939. On the geology and tectonics of the
Outokumpu ore field and region. Bull. Comm. 96ol.
Finlande 124, 9l p.
Vuorefainen, Y,, Häkli, T.A. & Papunen, H., 1972,
Argentian pentlandite from some Finnish sulphide deposits. Am. Mineral. 57, 137-145.
Väyrynen,
Weiser,
T., 1967. Zinck- und
Vanadium-führende
Chromite von Outokumpu, Finnland.
234-243.
N. Jb.
Mh.