Name
Moukkori
Alternative names
Housuvaara
DATA UPDATED
9.2.2006
Belt
Suomussalmi
LOCATION
Geological domain
Archaean
Site photo
Regional map
Map sheet
451309
Northing (kkj)
7243900
Easting (kkj)
4480850
Latitude
65.2903558N
Longitude
29.58612169E
Municipality
Suomussalmi
Nearest town, roads 55 km NE from Suomussalmi. 5 km from sealed road, a gravel road to
the area.
MINING
Exploration licence
no
4876/1–2, 6950/1,
7980/1–4
Present holder
Nordic Mines AB (2005–)
Previous holders
Geological Survey of Finland (GTK), Endomines Oy (2000–2005)
Mining concession
no
Mine photo 1
Mine photo 2
Mine photo 3
Mine photo 4
Status of
development
Prospect
When mined
Resources
0.0034 Mt @ 13.4 ppm Au [5]. Indicated 0.0034 Mt @ 13.4 ppm +
inferred 0.017 Mt @ 10 ppm (cutoff 2 ppm) [13].
Deposit size (Mt)
0.024
Reference (size)
[13]
Total in-situ gold
(kg)
220
Reference (in-situ
Au)
[13]
Total gold
production (kg)
Reference (gold
prod)
Production of other
metals
Extent of
mineralisation
Lodes
At least four parallel, subvertical lodes, plunging 42–45° to the S
[12,13,15].
Best sections
3.5 m @ 39 ppm Au [13,14].
EXPLORATION
Discovery year
1990
Discovery
By GTK: a tiny mineralised outcrop found in a forest road ditch, during
exploration for base metals [4,7,12]. First indication for gold in the
region were the auriferous glacial erratics found by an amateur
prospector in 1989 [15].
Exploration history
GTK (1990–97) [1,4,5,6,7,12]: Bedrock mapping, ground magnetic,
slingram, VLF-R, total intensity and IP survey, till geochemical and
stratigraphic survey, RC and diamond drilling, trenching, detailed
mineralogical study.
Section figure 1
Plan figure 1
Section figure 2
Plan figure 2
Section figure 3
Plan figure 3
Trench fig 1
Trench fig 4
Trench fig 2
Trench fig 5
Trench fig 3
Trench fig 6
Explor site photo 1
Explor site photo 2
Geophysical
response
Drilling
GTK: 17 diamond-drill holes, total 1746 m [5,7].
Elements analysed
[9]: Main components, Cl, Sn and Zr by XRF; Ag, As, Au, Bi, Pd, Sb, Se
and Te by GFAAS; Hg by wet-chemical method; B by DCP; Ba, Cd, Co,
Cr, Ga, La, Li, Mo, Nb, Ni, Pb, Rb, Sb, Sc, Sr, Th, Tl, U, V, W, Y and Zn
by ICP; S by Leco.
Primary dispersion
Secondary
dispersion
Primary anomaly
fig 1
Secondary anomaly
fig 1
Primary anomaly
fig 2
Secondary anomaly
fig 2
Primary anomaly
fig 3
Secondary anomaly
fig 3
Primary anomaly
fig 4
Secondary anomaly
fig 4
Primary anomaly
fig 5
Secondary anomaly
fig 5
Economic
evaluations
Resource estimates for Endomines by GTK in 2001 [13].
Exploration
geologist in charge
GTK: Erkki Luukkonen.
ORE
Siting of gold
80% of gold occurs as free grains (avg. grain size 25 microns, locally up
to millimetres in diameter) with gangue minerals, chiefly with quartz in
quartz veins, 15% is as inclusions in practically all sulphides and
tellurides, and some gold is in the lattice of the tellurides
[1,3,5,12,13,16].
Fineness
6.1–13.4% Ag; inclusions: 18.4–22.4% Ag [1].
Major opaques
Pyrrhotite [1,4,7,12].
Minor opaques
Marcasite, pyrite, galena, sphalerite, chalcopyrite, altaite, hessite,
volynskite, tsumoite, petzite, cervellite, gold, rutile, goethite [1,4,7,12].
Gangue
Quartz, scheelite, tourmaline [2,3,7,12].
Ore miner. photo 1
Ore miner. photo 5
Ore miner. photo 2
Ore miner. photo 6
Ore miner. photo 3
Ore outcrop photo
1
Ore miner. photo 4
Ore outcrop photo
2
Ore composition
Diamond-drill core [9]: 36.00 ppm Au, 6.90 ppm Ag, 5.2 ppm As, 33
ppm B, 241 ppm Ba, 920 ppm Bi, 26.5 ppm Co, 110 ppm Cu, 13 ppb Hg,
26.2 ppm Li, 2.1 ppm Mo, 26.3 ppm Ni, 124 ppm Pb, 59 ppm Rb, 10700
ppm S, 0.19 ppm Sb, 0.58 ppm Se, 192 ppm Sr, 2.20 ppm Te, 2.1 ppm
Th, 0.40 ppm Tl, 1.2 ppm U, 210 ppm V, 2 ppm W, 30 ppm Y, 117 ppm
Zn, 108 ppm Zr; 63.3% SiO2, 1.04% TiO2, 10.38% Al2O3, 9.82%
Fe2O3, 3.28% MgO, 5.60% CaO, 1.47% Na2O, 1.90% K2O, 0.13%
P2O5.
Enriched elements
Au, Ag, As, B, Bi, CO2, K, Pb, S, Te [9].
Ore fluid
Low salinity H2O-CO2±CH4 fluid(s); fluid inclusions: homogenisation T
= 195–235°C, min. pressure <2.5 kbar [2,16].
Stable isotopes
Pb isotope data
Pb-Pb data suggest lead originating from upper crust [15].
GEOLOGY
Geological setting
The deposit is in the Tormua Schist Belt which forms the NE part of the
late Archaean Suomussalmi Greenstone Belt and is in the rocks of the
3.0–2.8 Ga Luoma Group of the greenstone belt [7,10,11,12].
Major host rocks
"Uralite-porphyrite" [6,12].
Minor host rocks
Intermediate metatuffite [4].
Intrusives
Ca. 2700 Ma granitoids (syn-D3) and Palaeoproterozoic dolerites have
intruded into the supracrustal sequence [15].
Regional geol map
1
Outcrop photo 1
Regional geol map
2
Outcrop photo 2
Local geology map
1
Outcrop photo 3
Local geology map
2
METAMORPHISM
Metamorphic
history
Metamorphic grade Amphibolite facies [4].
Metamorphic
mineral assemblage
Plagioclase-hornblende-biotite-quartz ± K feldspar, ilmenite [1].
Metamorph photo 1
Metamorph photo 2
STRUCTURE
Structural style
Ductile(-brittle) [2,4,12].
Closest major shear A NNE-trending shear zone at the eastern boundary of the greenstone
belt, 1 km SE from the deposit [12].
Controlling
structure
The mineralisation is within a second-order D3 fault zone, in the axial
plane of a chevron-type F3 fold [3,5,7,12].
Deformation
history
At least, four deformation stages during the late Archaean and two
deformation stages during the Palaeoproterozoic time detected in the
area; the controlling structure is related to the third phase (D3) of the
regional structural evolution during the Archaean [1,3,7,15]. The latest
Archaean stage, D4, has deformed the gold mineralisation [3]. Age of D2
is probably 2820±15 Ma [15]. The D3 started as a plastic stage,
dominantly dextral folding and formation of strong N-trending shear
zones; this is partially overprinted by the NW-trending D4 foliation under
retrograde conditions [14]. Syn-D3 granodiorite suggests an age of ca.
2718 Ma for the D3 stage [15].
Ore fabric
Veins
Structure photo 1
Quartz veins with variable amount of sulphides [1,3,6,12].
Vein photo 1
Structure photo 2
Vein photo 2
Structure photo 3
Vein photo 3
ALTERATION
General alteration
Formation of the mineral assemblage chlorite-sericite-epidote-calcitequartz-rutile-ilmenite-pyrrhotite [1,2,12].
Proximal alteration
Mineral assemblage quartz-biotite-epidote(?)-chlorite-plagioclase-K
feldspar-sericite-calcite-pyrrhotite [1].
Intermediate
alteration
Distal alteration
The most distal alteration is probably indicated by the appearance of
tremolite ± epidote and titanite [1].
Zonation figure
Prox alteration
photo 1
Alteration photo 1
Prox alteration
photo 2
Alteration photo 2
Intermed alteration
photo
Alteration photo 3
Distal alteration
photo 1
Post-mineralisation
modifications
Post-mineralisation(?) D4 deformation [12]. Possibly, a retrograde
overprint at greenschist-facies PT conditions [2]. Palaeoproterozoic
dolerites have no thermal or alteration effect on their Archaean country
rocks [15].
TIMING
[2,15]: Hydrothermal titanite gives an U-Pb age of 2676±20 Ma [2,16].
This timing as the age for mineralisation is supported by structural
evidence, and be considered as a minimum age for mineralisation [15].
GENETIC
MODEL
[2,12,14,15]: Formed soon(?) after the peak metamorphic event under
slightly retrograde conditions near the ductile-brittle and amphibolitegreenschist facies transition zones, in still dominantly ductile regime,
during late-Archaean cratonisation. Deposition of gold occurred
primarily as a consequence of sulphidation of iron from the mafic country
rock. Timing fits with late-D3 or D4 deformation [15]. Fluid inclusions
suggest a single-event mineralisation at about 2–3 kbar, 300–350°C [16].
GENETIC TYPE
Orogenic 'mesothermal' [14]
References
1. Chernet, T. 1994. Ore mineralogy of the Moukkori gold prospect. Geol. Surv. Finland, Report
M19/4513/-94/1/42. 16 p.
2. Poutiainen, M. & Luukkonen, E. 1994. The geology and fluid inclusion studies of some
epigenetic gold deposits in the Archean Kuhmo and Suomussalmi greenstone belts, eastern
Finland. In: M. G. Izquierdo, A. M. C. Suarez, G. M. Guevara, D. Vanko & G. J. C. Viaggio
(eds) Fifth Biennial Pan-American Conference on Research on Fluid Inclusions, Cuernavaca,
Morelos, Mexico, May 19–21, 1994. Abstracts, 77–78.
3. Luukkonen, E. 1993. Kultamineralisaatio Suomussalmen ja Kuhmon vihreäkivivyöhykkeellä.
In: P. Nurmi (ed.) Itä-Suomen kultaesiintymät. Ekskursio-opas. Vuorimiesyhdistys, Sarja B, no.
54, 33–35. (in Finnish)
4. Pietikäinen, K. 1998. Personal communication 14/9/1998.
5. Ministry of Trade and Industry 1998. International tender notice. Tormua gold prospect,
Suomussalmi, Finland. Press release 6/10/1998.
6. Luukkonen, E. 1998. Personal communication 27/10/98.
7. Luukkonen, E., Heino, T., Tenhola, M., Niskanen, M. & Hartikainen, A. 1997.
Tutkimustyöselostus Suomussalmen kunnassa valtausalueella Saarilampi 1 (kaivosrekisteri
5351/1), Housuvaara 1–2 (kaivosrekisteri 4876/1–2), Mullikko 1 (kaivosrekisteri 5029/1), Pahka
1 (kaivosrekisteri 5029/2/1) ja Pahkalampi 1 (kaivosrekisteri 5232/1) suoritetuista
kultamalmitutkimuksista vuosina 1990–1997. Geol. Surv. Finland, Report M06/4513/-97/1/10.
21 p. (in Finnish)
8. Luukkonen, E., Pajunen, M. & Poutiainen, M. 1992. Kuhmo–Suomussalmen alueen arkeeisen
kallioperän rakenne-evoluutio ja Au-aiheet. In: E. Ekdahl (ed.) Suomen kallioperän kehitys ja
raaka-ainevarat. Vuorimiesyhdistys, Sarja B, 51, 11–12.
9. Bornhorst, T. & Nurmi, P. (1999) Personal communication 20/1/1999.
10. Luukkonen, E. 1992. Late Archaean and Early Proterozoic structural evolution in the
Kuhmo–Suomussalmi Terrain, eastern Finland. Annales universitatis Turkuensis. Ser. A. II 78,
1–37.
11. Sorjonen-Ward, P., Nironen, M. & Luukkonen, E. 1997. Greenstone associations in Finland.
In: M. J. de Wit and L. D. Ashwal (eds) Greenstone Belts. Clarendon Press, Oxford. 677–698.
12. Luukkonen, E. (ed.) 1998. Suomussalmen, Kuhmon ja Kostamuksen arkeeiset
vihreäkivivyöhykkeet ja niihihn liittyvä malminmuodostus. Ekskursio-opas. Vuorimiesyhdistys,
Sarja B, No 66, 40 p. (in Finnish)
13. Parkkinen, J. 2001. Quality control of mineral resource estimates: Laivakangas, Hosko,
Kuivisto E, Other, Osikonmäki, Pirilä, Housuvaara, Pahkalampi. Geol. Surv. Finland, Report. 27
p.
14. Papunen, H., Halkoaho, T., Liimatainen, J. & Luukkonen, E. 2001. Metallogeny of the
Archaean Tipasjärvi–Kuhmo–Suomussalmi greenstone belt, Finland. AGSO – Geoscience
Australia, Record 2001/37, 456–458.
15. Luukkonen, E., Halkoaho, T., Hartikainen, A., Heino, T., Niskanen, M., Pietikäinen, K. &
Tenhola, M. 2002. Itä-Suomen arkeeiset alueet –hankkeen (12201 ja 210 5000) toiminta vuosina
1992–2001 Suomussalmen, Hyrynsalmen, Kuhmon, Nurmeksen, Rautavaaran, Valtimon,
Lieksan, Ilomantsin, Kiihtelysvaaran, Enon, Kontiolahden, Tohmajärven ja Tuupovaaran
alueella. Geol. Surv. Finland, Report M19/4513/2002/1. 265 p. (in Finnish, 130 MB)
16. Poutiainen, M. and Partamies, S. 2003. Fluid inclusion characteristics of auriferous quartz
veins in Archean and Paleoproterozoic greenstone belts of eastern and southern Finland. Econ.
Geol. 98, 1355–1369.