nalunaq gold mine - geus

No. 11 - February 2008

The Nalunaq Gold Mine

GO_11_1.qxp:GO-02 copy.qxp 12/02/08 10:32 Side 1

’Nalunaq’ the Greenlandic name ofGreenland’s first gold mine means theplace that is hard to find. It is locatedin Kirkespirdalen (Church steeple val-ley) near the town of Nanortalik.Since the 1970s a number of signifi-cant gold occurrences in several placesin Greenland have been found anddescribed. The Nalunaq deposit is theresult of thorough geological workthat included ten years of explorationprior to commercial mining. In 2004the mining company Crew Gold Cor -poration was granted the final licenceto exploit the gold deposit at Nalu -naq, of which the operations are car-ried out by the Nalunaq Gold MineA/S. The Nalunaq mine was inaugurat-ed on 26 August 2004 as the first goldmine in Greenland.

Introduction

Gold was early on the list of mineral re -sources that were desirable for exploitationin Greenland. Today there are several goldoccurrences known in Greenland. These areprimary in-situ deposits of gold. Secondarydeposits of gold, i.e. placer gold, have notbeen found in Greenland.

Over the last three decades a number ofsignificant gold mineralised areas have beendiscovered and described. One of the firstwas the Tartoq occurrence in South Green-land, and subsequently new occurrenceswere found in the Disko Bugt area, in theGodthåbsfjord area and at the SkærgaardIntrusion in East Greenland. In 1992 the dis-covery at Kirkespirdalen in the very south ofGreenland was made, which 12 years laterserved as the background for the establish-ment of the first modern gold mine inGreenland, the Nalunaq Mine. The datagathered on the gold mineralisation inKirkespirdalen led to many finds of othergold occurrences in the region and now thearea is regarded as a major gold province.

Geological setting

The geological setting of the Nalunaq goldmine is the south Greenland basement,where it is concluded that the Palaeopro-terozoic Ketilidian juvenile orogen evolvedduring northward subduction of an oceanicplate under the southern margin of theArchaean craton. The evolution of theKetilidian orogen spans from 1850 Ma to1725 Ma. The orogen is subdivided intofour domains. The central part of theKetilidian orogen is dominated by one large,multi-phase, continental calc-alkalinebatholith, the Julianehåb batholith, which isemplaced (1854–1795 Ma) along thesouthern margin of the North Atlantic cra-ton over a north-dipping subduction zone.The major phases of the deformationformed several NNE- or NE-trending, sinis-tral shear zones through the batholith.

The region north of the batholith isnamed the Border Zone and consists ofreworked Archaean basement of the cratonand unconformable overlaying Ketilidiansupracrustal rocks, which become progres-sively involved in the Ketilidian metamor-phism and deformation towards the south.These well-preserved (1800 Ma) Ketilidiansupracrustals are located on Midternæs and

in Grænseland within the north-westernBorder Zone.

The region south of the batholith com-prises extensive areas of supracrustal rocks,the Psammite and Pelite Zones. Thesupracrustal rocks occupy a minimum widthof 100 km and with an estimated pre-ero-sional thickness of over 15 km. The Psam -mite Zone rocks include basic volcanic rocks,variably migmatised pelitic and semi-peliticrocks, calcareous metasediments, beddedmassive-pyrrhotite/graphitic-cherts, dole -rites, syn- to post-kinematic appinite dykesas well as post-kinematic rapakivi granites.The psammites are interpreted to representintra- and fore-arc sediments, eroded fromthe Juliane-håb batholith and deposited influvial and shallow marine environmentsbetween the batholith and an oceanic envi-ronment to the south. The Pelite Zone atthe southern tip of Greenland comprises

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Aerial view of the Nalunaq mining camp and the road to the mine adits (2006).

The Nalunaq Gold Mine

View towards the south-west of the valley withthe Nalunaq gold mine (centre right) and the 9km connecting road to the harbour at theSaqqa Fjord (centre upper).


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mainly flat-lying, intensely migmatisedpelitic rocks. The pelitic rocks consist mainlyof turbidite sediments, deposited in deeperoffshore settings compared with the fluvialand shallow marine environments of thepsammites. The mafic volcanic rocks andgranitoids are gold bearing, as observed atthe Nalunaq mine.

The Nalunaq deposit is a high-gradegold mineralisation associated with quartz-veins in a major shear zone. As genetictype, the deposit is an orogenic-type goldmineralisation (mesothermal lode gold),hosted in Palaeoproterozoic amphibolitefacies metavolcanic rocks. Visible gold isfound in sheeted quartz veins which arelocated in a large-scale shear structure thatappears to be related to regional thrusting.

The most pronounced structure at Nalunaqis a narrow zone of ductile shearing sur-rounded by relatively brittle margins. Thegold carrying quartz veins vary from 0.05 mto 1.8 m in width and often display pinchand swell structure. The so-called Main Veinwithin the deposit is hosted in a 1–2 mwide shear zone with a remarkably constantorientation.

Exploration history

The exploration prior to commercial miningbegan at the end of the 1980s when geolo-gists from the exploration company CarlNielsen A/S observed small flakes of gold inthe gravel at the coast at the foot of themountain named Kirkespiret. The systematic

geological mapping of the area was carriedout already in the 1960s by the GeologicalSurvey of Greenland (later GEUS) and thusprovided a good foundation for the explo-ration work. In 1990 the Greenland-Danishexploration company Nunaoil A/S wasgranted an exploration licenses and thecompany’s chief geologist pursued the ideathat loose gold at the coast must be due toin-situ gold in the mountains. In 1992 pri-mary gold was finally located almost 500 mabove sea level on the slopes of the valleyKirkespirdalen.

The gold was visible in outcroppingquartz veins and appeared to occur over anarea of 800 m in length. Later, new playersjoined the exploration, carrying out the firstdrilling at the location, and in 1998 the first

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T H E N A L U N A Q G O L D M I N E

Geological map of South Greenland with the location of the Nalunaq Gold Mine.

500 km

60°N

61°N

62°N

Gardar intrusions, basalt and sandstone

Inland Ice, local ice caps and glaciers

Undifferentiated basement100 km

46° W48° W 44° W42° W

Ketilidian orogen

Archaean

Arsuk Ø

Grænseland

Midternæs

Qoornoq

Kobberminebugt

Nørrearm

Lindenow Fjord

Danell Fjord

Napasorsuaq Fjord

Nanortalik

Qaqortoq

Saarloq

Niaqor-naarsuk

Søndre Sermilik

Tasermiut

Kap FarvelEggers Ø

Prins Christian Sund

Sârdloq shear zone

Kangerluluk

Fore-arc deposits, mainly metagreywacke and granites (Pelite Zone)

Fore-arc deposits, mainly metaarkose (Psammite Zone)

Julianehåb batholith and related intrusions

Rapakivi granite suite and related intrusions

Metasedimentary and metavolcanic rocks (Border Zone)

Sermiligaarsuk

Ivituut

FORELAND

BORDER ZONE

JULIANEHÅBBATHOLITH

FORE ARC

PSAMMITE ZONE

PELITEZONE

Nalunaq Gold MineNalunaq Gold Mine


investigation adit was established. Fromhere it was possible to obtain enough oreto carry out pilot production and process-ing. The UK-based Crew Gold Corporationtook over the majority of the shares in thegold exploration in 1999, whilst 17.5 percent were held by the Greenland companyNunamin-erals A/S. On 26 August 2004 themine was officially opened. In November2007 Crew Gold Corporation acquired allshares in the gold mine.

The terrain surrounding the mine isalpine with mountain peaks reaching1,200–1,600 m above sea level. TheNalunaq Mountain is 1,340 m high and islocated in a wide glacial valley reachinginto the Saqqa Fjord about 9 km fromthe mine site. Deep fjords allow access forshipping and the overall climate is sub -

arctic allowing full operations around theyear.

Preparing a mine

Crew Gold Corporation was granted thefinal licence to exploit the gold deposits atNalunaq, which was operated by theGreenland company Nalunaq Gold MineA/S. This licence does not include on-siteextraction of the gold from the ore on-site,but rather the company will ship the ore toa processing plant abroad. During the firsttwo years, the extraction was carried out inSpain at the plant of Rio Narcea GoldMines. Following this, the extraction wasmoved to Canada at the Nugget Pond plantin Newfoundland, which Crew Develop-ment had acquired in 2006. The harbour

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level 350

level 400

level 450

South block

Target block

Mountain block

Mining camp

Fault

Exposed quartz vein

The mining camp at Nalunaq. The wooden bar-racks and facilities are situated along the riverdraining the valley. In the front, one of the 25-tonne trucks en route to the mine.

View of the mining area at Nalunaq.


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facilities constructed at Nalunaq take advan-tage of the fact that there is deep water atthe coast enabling large ore vessels to dockand to be loaded directly from the ore stor-age facility at the harbour.

The Crew Gold Corporation owns 100%of the Greenland limited liability company,Nalunaq Gold Mine A/S (NGM). The mininglicense, granted by the Governments inGreenland and Denmark in 2004, has aduration of 30 years. The license covers anarea of 16 km² around the mine site. In 2004 the basis for the operation of themine, according to Nalunaq Gold Mine A/S,was estimated to be ore reserves of400,000 t with a gold grade of 21 gramsper tonne. Furthermore there is indicationof extra resources at 1,670,000 t with an

average gold grade of 18 grams per tonne.Production in 2006 comprised 108,000 t ofore with an average grade of gold of 17.9

grams per tonne. Depending on the pro-duction rate in the mine, there will probablybe enough ore for an operating period of

Underground exploration drilling inside theNalunaq mine.

The study of an underground face of the gold bearing quartz vein in the Nalunaq mine.

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Exploration drilling at the slope of the Nalunaqmountain on the northern side ofKirkespirdalen looking towards the north-east.


between three and ten years. Nalunaq isequipped with a fully functional assay labo-ratory, consisting of a preparation lab, a

wet chemistry lab and an assay section withcomputerized AAS instrumentation.

Mine operations

The camp accomodate 100 people to man-age the operation within the mine, in thecamp and harbour. Mining operations andmaintenance are contracted to Procon Mi -ning and Tunnelling Ltd. of Canada on alabour hire basis. Mining equipment isowned by NGM and the Crew Gold Cor -poration. Locally contractors out of Nanor -talik are engaged for surface ore haul, on-site construction work, catering and janitor-ial work. In total, over 35% of the employ-ees are locally hired.

On-site, the ore is hauled by 25-tonnetrucks to a 60,000 t capacity stockpile areaat the harbour facility established on theSaqqaa fjord about 11 km from the minesite. When there is sufficient ore, a ship isrequested from Western Bulk Carriers withwhom the mine has an annual contract.Bulk carriers with 20–30,000 t capacity areloaded at the Nalunaq port for delivery tothe Nugget Pond processing facilities.

The Nalunaq mine has posed consider-able challenges due to the geometry of the

Long-hole drilling

Charging long-holes

© Carsten E. Thuesen, GEUS

Access cross-cuts

Sub-leveldevelopment

Broken ore

Slot raise

10 m verticalsub-level interval

Pillar

Mined stopes

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An underground view of a hanging wall of a mined-out 1.2 m stope.

Schematic 3-D presentation of the miningmethod used with demonstration of the long-hole open stoping system. 3D figure: Carsten E.Thuesen, GEUS.



Main Vein. The typical situation in the mineis a narrow average vein width of 0.7 m,with a 30–40 degree dip. The narrow widthcalls for a high degree of drilling and blast-ing accuracy to prevent dilution, and thedip both precludes efficient footwall layoutsfor mechanised mining and requires addi-tional rock handling activities to ensure thatthe ore is successfully transferred to thebottom of the stope for later pick-up.

The preferred mining method is longholeopen stoping, which comprises develop-ment of sub-levels horizontally along strikeat 10 m intervals in vertical spacing, result-ing in ore blocks of about 14–16 m lengthon dip. The sub-levels are either mined as afull face or in two cuts separating the oreand the waste. The block between two sub-levels is then subdivided into 15 m widestopes between 1.5 m rib pillars for stability.A stope thickness of 1.4 m is endeavouredand each stope is drilled with blast holesup-dip using a ring box pattern. Followingstoping and removal of the ore, the stopehas to be cleaned of any residual fine ore,some of which is high grade. The resultingstope cavities are unsupported and open to

the sub-levels above and below. Nalunaqore production rate is carried out close tothe planned aim of 500 t per day.

To access the sub-levels, from which alloperations are carried out, a ramp and anumber of mine adits have been excavated.Ore passes are used for transfer of minedore.

Gold extraction

The amount of gold in the ore is rathererraticly distributed (nugget effect) with anaverage of 18 grams of gold per tonne ofore, but there are locally very rich parts thatcontain as much as four to five kg of goldper tonne of ore. Due to the fact that thegold occurs in quartz veins, on average only0.7 m wide, the mining of the ore mayresult in a reduction of the gold content asit is impossible to avoid mixing of bedrock

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The layout of the Nalunaq Gold Mine with thethree main levels, drifts and raises in a 3-Dmodel presentation, November 2005.

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200.

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300.

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400.

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500.

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600.

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800.

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900.

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1000

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1100

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1200

.00

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100.00 Y

200.00 Y

300.00 Y

400.00 Y

500.00 Y

600.00 Y

700.00 Y

800.00 Y

300 Level

350 Level

400 Level

450 Level

7/11 2005

Rock sample of quartz vein rich in gold grains.




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with low gold content into the ore. Theminerals in the gold ore are dominated bymetallic gold. Various sulphide minerals inwhich gold occurs as impurities account forless than one per cent. This means thatwhen the gold is extracted, it 'only' has tobe released from the surrounding silicates(mostly quartz). In practice this is done bycrushing and subsequent gravity separationwhere the high density of gold is utilised(19.3 g/cm3). This process can achieve ahigh recovery rate of close to 100%. Oncethe gold has been extracted from the ore, itis easily melted and cast into ingots forcommercial sale. In practice smelting is car-

ried out in several stages so that theslag material (from silicate residues)and impurities of silver, bismuth, anti-mony and arsenic are removed beforethe final commercially tradable puregold (bullion) is produced. The smelt-ing process is carried out outside Greenlandat the smelting plant at Nugget Pond inCanada.

Concluding remarks

Nalunaq is a high-grade deposit of gold inquartz veins. The individual quartz veins arebetween 0.1–2.0 m thick, averaging 0.7 m.The gold-bearing structure has a regionalscale, and it is therefore expected that theamount of ore is much larger. Production ofgold from Nalunaq is targeted to amount tofour tonnes of gold per year.

In the wake of the successful start of themine it has been natural to seek for anextension of its productive life. In order toreach the goal of extending ore reservesexploration activities have been initiated inboth the mine area and in the surroundingareas with potentially gold-bearing rocks.Outside the mine area the mining company


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The Saqqa Fjord filled with icebergs. A bulk-carrier preparing for leaving with a full oreload. To the right the port and in the centre the road to the mining camp in Kirkespir-dalen. The landmark of the 1590 m high Kirkespiret mountain, is seen in the back-ground.

A working conveyor belt as part of the loadingsystem for the vessels at the harbour facility.

A docking bulk-carrier at the Nalunaq port. Close tothe pier is the location of the ore storage facility with anumber of ore piles. The road connection to theNalunaq mining camp can be followed along the coastline.


has been granted additional explorationlicences, which in total covers an area ofaround 500 km2. At present, activities with-in the licence area have proven occurrencesof gold mineralisation at a locality 20 kmSW of Nalunaq and on the Niaqornaarsukpeninsular around 20 km NW of Nalunaq.Additionally there are various indications ofgold at a number of other sites with corre-sponding geological environments.

Garde, A.A., Hamilton M.A., Chadwick B.,

Grocott J., & McCaffrey K.J.W. 2002: The

Ketilidian orogen of South Greenland: geo -

chronology, tectonics, magmatism, and fore-arc

accretion during Palaeoproterozoic oblique con-

vergence, Canadian Journal of Earth Sciences

39, 765–793.

Gowen, J., Christiansen, O., Grahl-Madsen, L.,

Pedersen, J. L., Petersen, J. S. & Robyn,T.L.

1993: Discovery of the Nalunaq gold deposit,

Kirkespirdalen, SW Greenland. International

Geology Review 35(11), 1001–1008.

Grammatikopoulos, T. A., Porrit, L., Petersen,

J.S. & Christensen, K. 2004: Mineralogical char-

acterisation and process mineralogy of gold bear-

ing rocks from the Nalunaq gold deposit,

Greenland. Applied Earth Science 113(3), 197–203.

Kaltoft, K., Schlatter, D.M. & Kludt, L. 2000:

Geology and genesis of Nalunaq Palaeo -

proterozoic shear zone-hosted gold deposit,

South Greenland. Applied Earth Science 109

(Section B), B23–B33.

Lind, M., Kludt, L. & Ballou, B. 2001: The Nalunaq

gold prospect, South Greenland: test mining for

feasibility studies. Geology of Greenland Survey

Bulletin 189, 70–75.

Stendal, H. & Secher, K. 2002: Gold mineralisa-

tion and gold potential in South Greenland.

Geology and Ore 1, 12 pp.

Stendal, H., Secher, K., Stensgaard, B.M.,

Schønwandt, H.K. & Thorning, L. 2005:

Greenland geological environments and mineral

resources. Copenhagen, Danmarks og Grønlands

Geologiske Undersøgelse Rapport 2005/8, 211 pp.

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Front cover photographUnderground view of a gold carrying

quartz vein in the Nalunaq mine. Blue

paint is marking the ore to be mined.

Bureau of Minerals and Petroleum(BMP)

Government of GreenlandP.O. Box 930

DK-3900 NuukGreenland

Tel: (+299) 34 68 00Fax.: (+299) 32 43 02

E-mail: [email protected]: www.bmp.gl

Geological Survey of Denmark and Greenland (GEUS)

Øster Voldgade 10DK-1350 Copenhagen K

Denmark

Tel: (+45) 38 14 20 00Fax.: (+45) 38 14 20 50E-mail: [email protected]: www.geus.dk

AuthorsK. Secher, H. Stendal & B.M.

Stensgaard

EditorKarsten Secher, GEUS

Graphic ProductionHenrik Klinge Pedersen, GEUS

PhotographsPhotos and illustrations: GEUS and

courtesy of the Nalunaq Gold Mine.

PrintedFebruary 2008 © GEUS

PrintersSchultz Grafisk

ISSN1602-818x

Key literature

An example of the use of Greenland gold: acouple of 22 K wedding rings with a Polar Bearmark visible. Artist: Goldsmith Nicolai Appel,Copenhagen, Denmark.

The first output: a 1 kilo Fine Gold bullion(No. A 00001) produced from the NalunaqGold Mine.


nalunaq gold mine - geus

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