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Modified: 14.08.2009

Laivakangas - Gold Database

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Name Laivakangas DATA UPDATED 12.9.2008
Alternative names Näädänmaa, Näädänmalmi, Kauniinhaudanmalmi, Kauniinhaudansuo
Deposit summary LAIVAKANGAS, in the Raahe-Haapajärvi area, is a deposit now (November 2006) under feasibility study and test mining by Nordic Mines Ab. The current in situ resource estimate is 20 tons of gold at the average grade of 2.4 g/t Au. It is a Palaeoproterozoic orogenic gold deposit comprising, at least, 18 lodes containing sets of auriferous, arsenopyrite-rich quartz veins. The main host rock is quartz diorite. All rocks have been metamorphosed to lower- or mid-amphibolite facies. Alteration is characterised by formation of diopside-biotite-hornblende-plagioclase-K-feldspar-quartz assemblage. The deposit is between two major NW-trending shear zones of the Raahe-Ladoga suture. Native gold as inclusions in arsenopyrite, loellingite, quartz and other silicates.
LOCATION
Geological domain Svecofennian Belt Raahe-Haapajärvi
Site photo laivakangas_pit_thumb Regional map laivakangasfig1_thumb
Map sheet 244107
Northing (kkj) 7160400 Easting (kkj) 2528200
Latitude 64.5407N Longitude 24.5839E
Municipality Raahe
Nearest town, roads 16 km SSE from Raahe, 50 km SW from Oulu. A sealed road 8 km from the area, a narrow gravel road to the area.
MINING
Exploration licence no 3181/1, 3463/1, 3649/1-2, 6122/1, 6571/1-5, 7803/1, 7979/1-2, 7992/1-3, 8045/1-5 Mining concession no 7803/1a
Present holder Nordic Mines AB (2005-)
Previous holders Outokumpu Oy (1980's), Endomines Oy (1997-2005)
Mine photo 1 laivakangas_testpit2005_th Mine photo 2  
Mine photo3   Mine photo 4  
Status of development Test mine
When mined 1985, 2005
Resources Measured: 2.94 Mt @ 2.12 ppm Au, indicated: 7.53 Mt @ 2.36 ppm Au, total inferred: 4.11 Mt @ 2.35 ppm Au and total low grade: 5.27 Mt @ 0.63 ppm Au [22]. Measured: 0.75 Mt @ 2.09 ppm Au, indicated: 9.53 Mt @ 2.34 ppm Au, inferred: 1.5 Mt @ 2.4 ppm Au + "B ore" with 4.5 Mt @ 0.6 ppm Au [20]. Measured: 0.75 Mt @ 2.09 ppm Au, indicated: 6.28 Mt @ 2.41 ppm Au, inferred: 2.81 Mt @ 2.2 ppm Au + "B ore" with 3.2 Mt @ 0.6 ppm Au [18]. Indicated + inferred: 3.1 Mt @ 2.6 ppm Au [15]. Indicated 0.3 Mt @ 3.3 ppm + inferred 0.2 Mt @ 5 ppm (cutoff 2 ppm) [12]. 0.7 Mt 4 ppm Au [5].
Deposit size (Mt) 14.58 Reference (size) [22]
Total in-situ gold (kg) 33710 Reference (in-situ Au) [22]
Total gold production (kg) 28 Reference (gold prod) [13]
Production of other metals  
Extent of mineralisation A few metres wide and a few tens of metres long at surface [3], open at the depth of 60 m [10,11,12].
Lodes The number of lodes reported is 18; they are 10–100 m long, on average 2.4 m wide, and have an ENE strike [12]. Main lodes are the larger Laivakangas N and the smaller Laivakangas S which appear to join together [12,17].
Best sections 1 m @ 92 ppm Au [15]. 14.85 m @ 1.9 ppm, 4 m @ 2.9 ppm, 1.9 m @ 3.3 ppm Au [14]. 2.2–13.4 m sections at 2.7–24.2 ppm Au [8].
EXPLORATION
Discovery year 1982
Discovery By Outokumpu. The first indication was an sample from a glacial erratic boulder found by an amateur prospector on 1980 [2,4].
Exploration history Outokumpu Oy (1980's) [2,3,4,6,10,11,12]: bedrock mapping, till and stream sediment geochemical survey, survey of glacial erratic boulders, till stratigraphy, magnetic and IP ground survey, percussion and diamond drilling, pilot plant tests, thin section studies.
Endomines Oy [10,11,12,14]: diamond drilling, pilot plant tests.
Nordic Mines [15,16,17,18,19,20]: diamond drilling, test mining, pilot plant tests.
Section figure 1 laivakangas_resource_model_2001_thumb Plan figure 1 laivakangas_metalzoning_finnas2007_th
Section figure 2 laivakangas_n_3d_model_thumb Plan figure 2  
Section figure 3 laivakangas_all_3d_model2006_th Plan figure 3  
Section figure 4 laivakangas_oreblocks_finnas2007_th Plan figure 4  
Trench fig 1   Trench fig 4  
Trench fig 2   Trench fig 5  
Trench fig 3   Trench fig 6  
Explor site photo 1 laivakangas_pit_thumb Explor site photo 2  
Geophysical response  
Drilling Outokumpu Oy (1980's): diamond drilling, total 6200 m in the area [2], 95 diamond-drill holes [12]. Drilling in profiles, information from two profiles where each hole is about 20–30 m apart and the distance between profiles is 25 m [4].
Endomines: 11 diamond-drill holes, total 803 m [12].
Total drilling by end of September 2005: 6957 m [15].
Nordic Mines (2005–): diamond drilling, total 13 km by 14 Aug 2006 [16,17].
Elements analysed SiO2, TiO2, Al2O3, Fe2O3, MnO, MgO, CaO, Na2O, and K2O by XRF; Ag, As, Au, Bi, Co, Cu, Fe, Hg, Ni, Pb, Te, Zn: by AAS; S by Leco [3].
Primary dispersion Good correlation between Au, As, Bi and Sb [2,3,6]. Other element pairs showing good mutual positive correlation are: Cu and Ag, As and Sb, and Te and Bi [3].
Secondary dispersion A distinct stream sediment Au, As and Sb anomaly, and Au and As anomaly in till [6].
Primary anomaly fig 1   Secondary anomaly fig 1 laivakangas_au_in_till_th
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 Feasibility study by Outokumpu Oy on 1990(?) [4]. Resource estimates for Endomines by GTK in 1999–2001 [10,11,12]. Preliminary feasibility study and upgraded resource estimates by Nordic Mines [15,16,18,19].
Exploration geologist in charge Outokumpu: Esa Sandberg, Endomines: Jaakko Liikanen, Nordic Mines: Peter Finnäs.
ORE
Siting of gold Gold occurs as native inclusions in quartz and other silicates (34% of all gold), and arsenopyrite and loellingite (64%; grain size 1–40 μm), minor gold (2%) is in maldonite and as inclusions in chalcopyrite; most of gold is in the quartz veins [2,3,6,12].
Fineness 95% Au, 1.7% Ag (avg.) [2,6].
Major opaques Arsenopyrite, loellingite [2,3,6].
Minor opaques Pyrrhotite, chalcopyrite, pyrite, cubanite, marcasite, sphalerite, maldonite, bismuth, hedleyite, gold, molybdenite [2,3,6]
Gangue Quartz, diopside, K-feldspar, plagioclase, biotite, scheelite [2,3,6].
Ore miner. photo 1 laivakangas7_thumb Ore miner. photo 5  
Ore miner. photo 2 laivakangas8_thumb Ore miner. photo 6  
Ore miner. photo 3   Ore outcrop photo 1 laivakangas6_thumb
Ore miner. photo 4   Ore outcrop photo 2  
Ore composition Diamond-drill core [1]: 4.95 ppm Au, 2.100 ppm Ag, 2200 ppm As, 5.6 ppm B, 283 ppm Ba, 14.2 ppm Bi, 71 ppm Co, 451 ppm Cu, 52 ppb Hg, 2.0 ppm Mo, 36 ppm Ni, <1 ppm Pb, 66 ppm Rb, 2800 ppm S, <0.3 ppm Sb, 2.2 ppm Se, 202 ppm Sr, 1.850 ppm Te, 1.7 ppm Th, 0.5 ppm U, 280 ppm V, 28 ppm W, 92 ppm Zn; 54.1% SiO2, 0.80% TiO2, 15.2% Al2O3, 10.4% Fe2O3, 6.14% MgO, 8.51% CaO, 2.82% Na2O, 1.56% K2O, 0.14% P2O5, 0.85% LOI.
Enriched elements Ag, As, Au, Bi, Hg, K (in mafic rock only), S, Se, Si(?), Te, W [1,3].
Ore fluid  
Stable isotopes  
Pb isotope data  
GEOLOGY
Geological setting The deposit is in a late-orogenic(?) quartz diorite and mafic metavolcanic rock [2,3,5,6,12]. The deposit is in a sequence of Palaeoproterozoic metavolcanic rocks intruded by synorogenic dykes, sills and plutons [5,6].
Major host rocks Quartz diorite and mafic metavolcanic rock [1,3]
Minor host rocks Granite [1,3]
Intrusives Quartz diorite dikes from the 1.89–1.87 Ga [9] synorogenic pluton cross cut the metavolcanic rock, but predate mineralisation. Up to 20 cm wide, late-orogenic(?), granite dikes cut across the quartz diorite dikes and gold mineralisation [1,2,3,5,6], and a large granite body is immediately to the west of the mafic rock and the deposit [12].
Regional geol map 1 laivakangasfig1_thumb Outcrop photo 1 laivakangas3_thumb
Regional geol map 2   Outcrop photo 2 laivakangas_dyke_thumb
Local geology map 1 laivakangas_n_localgeol_3d_thumb Local geology map 2 laivakangas_s_plangeology_drilling_th
Local geology map 3 laivakangas_localgeology_finnas2007_th
METAMORPHISM  
Metamorphic history  
Metamorphic grade Amphibolite facies, 575±50°C, 5±0.5 kbar [3]. On the other hand, the presence of diopside indicates mid-amphibolite facies conditions. "Medium-grade" metamorphism in the reference [2].
Metamorphic mineral assemblage Mafic metavolcanic rock: plagioclase-hornblende-biotite ± quartz, K feldspar, titanite, epidote, ilmenite [3].
Quartz diorite: plagioclase-hornblende-quartz-biotite ± K feldspar, titanite [3].
Metamorph photo 1   Metamorph photo 2  
STRUCTURE  
Structural style Brittle-ductile [2,3].
Closest major shear The mineralisation is located between NW-trending major (>100 km long) shear zones of the Raahe-Ladoga suture zone [5,6,7].
Controlling structure A set of parallel, 1–150 cm wide, E- or ENE-trending, subvertical shear zones [2,12].
Deformation history  
Ore fabric  
Veins Auriferous arsenopyrite-quartz veins [1,2,3] which have a dip of 70–85° to the ENE [10].
Structure photo 1 laivakangasfig2_thumb Vein photo 1 laivakangas5_thumb
Structure photo 2 laivakangas6_thumb Vein photo 2 laivakangas_n_oresample_1_thumb
Structure photo 3   Vein photo 3 laivakangas_ore_outcrop_finnas2007_th
ALTERATION  
General alteration Formation of epidote, biotite, K feldspar, quartz and arsenopyrite [3]. Alteration is, apparently, more intense in the mafic metavolcanic rock than in the quartz diorite [3].
Proximal alteration Diopside-biotite-hornblende-plagioclase-K-feldspar-biotite-quartz-epidote assemblage; a diopside band forms the most proximal subzone, next to the veins, this is followed by a hornblende-dominated subzone [2,3,6].
Intermediate alteration  
Distal alteration  
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  
TIMING The deposit post-dates the intrusion of synorogenic quartz diorite, but predates late-orogenic(?) granite dikes [3].
GENETIC MODEL Loellingite is surrounded by a arsenopyrite rim: the deposit is formed at temperatures where loellingite is stable, although arsenopyrite thermometry only gives 370°C [2]. Features described in [2,3,4,5,6] indicate an orogenic "mesothermal" mineralisation formed under amphibolite-facies PT conditions. Metal zoning (Au-As, Au-Cu, and Au-Mo-W zones) suggest an granitoid intrusion-related (non-skarn) deposit type [21].
Genetic type Orogenic References [2,3,4,5,6]
Alternative genetic type 1 Granitoid-related (non-skarn) References [21]
Alternative genetic type 2   References  

References

1. Nurmi, P. A., Lestinen, P. & Niskavaara, H. 1991. Geochemical characteristics of mesothermal gold deposits in the Fennoscandian Shield, and a comparison with selected Canadian and Australian deposits. Geol. Surv. Finland, Bulletin 351. 101 p.
2. Mäkelä, M. & Sandberg, E. 1985. Raahen Laivakankaan kultaesiintymä. The gold occurrence at Laivakangas, Raahe. Geologi. 37, 5–8.
3. Mäkelä, M. 1984. Raahen Laivakankaan kvartsi-arseenikiisukultaesiintymä. Unpublished MSc thesis. University of Turku. 105 p. (in Finnish)
4. Korkalo, T. 1991. Kaivoslain 19 pyk. mukainen tutkimustyöselostus: Raahen kaupunki: Pirttihaudankangas, Siljanneva, Pirttivaara, Kauniinhaudansuo. Outokumpu Oy, Report 080/2441, 2432/TTK/91. 3 p. (in Finnish, 680 KB)
5. Mäkelä, M., Sandberg, E. & Rantala, O. 1988. Proterozoic, gold-bearing vein occurrences associated with the granitoids in western Finland. In: A. D. T. Goode et al. (comp.) Bicentennial Gold 88, Melbourne, Victoria, May 16–20, 1988: Extended abstracts. Poster programme. 1. Geological Society of Australia. Abstracts Series 23, 153–155.
6. Mäkelä, M., Sandberg, E. & Rantala, O. 1988. Geochemical exploration of gold-bearing veins associated with granitoids in western Finland. In: D. R. MacDonald & K. A. Mills (eds) Prospecting in Areas of Glaciated Terrain – 1988: Papers presented at the Eighth International Symposium on Prospecting in Areas of Glaciated Terrain, Halifax, Nova Scotia, August 28 – September 3, 1988: Canadian Institute of Mining and Metallurgy. 255–270.
7. Korsman, K., Koistinen, T., Kohonen, J., Wennerström, M., Ekdahl, E., Honkamo, M., Idman, H. & Pekkala, Y. (eds.) 1997. Suomen Kallioperäkartta = Berggrundskarta över Finland = Bedrock map of Finland 1:1 000 000. Geol. Surv. Finland.
8. Endomines Oy. 1999. www.endomines.fi on 09/12/99
9. Korsman, K. (ed.) & Glebovitsky, V. (ed.) 1999. Raahe-Ladoga Zone structure-lithology, metamorphism and metallogeny: a Finnish-Russian cooperation project 1996–1999. Map 2: Metamorphism of the Raahe-Ladoga Zone 1:1000000. Geol. Surv. Finland.
10. Parkkinen, J. 1999. Ilomantsin Hoskon ja Raahen Laivakangas: mineraalivarantoarvioiden menetelmätarkistus Endomines Oy:lle. English summary: The Hosko gold prospect at Ilomantsi and the Laivakangas gold occurrence at Raahe: technical revision of evaluations for Endomines Oy. Geol. Surv. Finland, Report M10/1999/4. 19 p. (38.4 MB)
11. Parkkinen, J. 2000. Laivakankaan kulta-aihe. Mineraalivarantoarvion tarkistus. Geol. Surv. Finland, Report M19/2441/2000/1. 7 p. (in Finnish, 3.2 MB)
12. Parkkinen, J. 2001. Quality control of mineral resource estimates: Laivakangas, Hosko, Kuivisto E, Other, Osikonmäki, Pirilä, Housuvaara, Pahkalampi. Geol. Surv. Finland, Report. 27 p.
13. Puustinen, K. 1995. Suomen malmikaivokset vuosina 1530–1994. Geol. Surv. Finland, Report M10.1/-95/1. 96 p. (in Finnish)
14. Endomines Oy. 2005. www.endomines.fi in 12/12/2005.
15. Nordic Mines Ab. 2006. www.nordicmines.se/laiva.php in 16/03/2006.
16. Nordic Mines Ab. 2006. Press release 05/06/2006.
17. Finnäs, P. 2006. Personal communication in 14 August 2006.
18. Nordic Mines Ab. 2007. Press release 08/03/2007. 2 p. (in Swedish, 115 KB)
19. Nordic Mines 2007. Pressmeddelande den 4 juli 2007. (in Swedish, 1.1 MB)
20. Nordic Mines 2007. Pressmeddelande den 13 november 2007. (in Swedish, 1.1 MB)
21. Nilsson, M. & Finnäs, O. 2007. Written communication, 28 November 2007.
22. Nordic Mines 2008. Pressmeddelande den 27 februari 2008. (in Swedish)
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