Norsk versjon
	THE ORE DATABASE
	Deposit 1833 - 076 Mofjellet
	(Object Id: 2774) (Last updated: 19.03.2024)

Products

	Element/product	Crude ore grade or quality	Reg. date
	Ag	10 ppm	19.03.1992
	Au	0.3 ppm	19.03.1992
	Cu	0.31 %	19.03.1992
	Pb	0.71 %	19.03.1992
	Zn	3.61 %	19.03.1992

Operations

	From - To	Activity	Comments
	1852 - 1862	Test mining
	1899 - 1904	Test mining
	1912 - 1914	Test mining
	1918 - 1920	Test mining
	1926 - 1987	Regular production

Mineralization

	Genesis:	Volcex	Form:	Ruler
	Main texture:	Banded	Min. distribution:	Semi-massive (20-50 % ore minerals)

Main grain size:

Medium grained (1-3 mm)

Main alteration:

Sericitisation

	Strike/Dip:		Direction:	87
			Plunge:	0

Stratigraphic classification of host rock

Era:

Period:

	Province:	Caledonides
	Geotec.unit:	Rødingsfjell Nappe Complex
	Tectonic complex:	Uppermost Allochthon
	Igneous complex:

Group:

Mofjell Group

Formation:

Mineralogy

	Relationship	Mineral	Amount
	Gangue mineral	Quartz	Major mineral (>10%)
	Gangue mineral	Calcite	Major mineral (>10%)
	Gangue mineral	Epidote	Subordinate mineral (1-10%)
	Gangue mineral	Biotite	Subordinate mineral (1-10%)
	Gangue mineral	Kyanite	Subordinate mineral (1-10%)
	Gangue mineral	Hornblende	Subordinate mineral (1-10%)
	Gangue mineral	Muscovite	Subordinate mineral (1-10%)
	Gangue mineral	Plagioclase	Subordinate mineral (1-10%)
	Gangue mineral	Garnet	Subordinate mineral (1-10%)
	Gangue mineral	Fluorspar	Accessory mineral (<1%)
	Gangue mineral	Chlorite	Accessory mineral (<1%)
	Gangue mineral	Barite	Accessory mineral (<1%)
	Ore mineral	Sphalerite	Major mineral (>10%)
	Ore mineral	Pyrite	Major mineral (>10%)
	Ore mineral	Chalcopyrite	Subordinate mineral (1-10%)
	Ore mineral	Pyrrhotite	Subordinate mineral (1-10%)
	Ore mineral	Galena	Subordinate mineral (1-10%)
	Ore mineral	Molybdenite	Accessory mineral (<1%)
	Ore mineral	Gudmundite	Accessory mineral (<1%)
	Ore mineral	Dyscrasite	Accessory mineral (<1%)
	Ore mineral	Bournonite	Accessory mineral (<1%)
	Ore mineral	Boulangerite	Accessory mineral (<1%)
	Ore mineral	Arsenopyrite	Accessory mineral (<1%)
	Ore mineral	Tennantite	Accessory mineral (<1%)
	Ore mineral	Hessite	Accessory mineral (<1%)
	Ore mineral	Gold	Accessory mineral (<1%)
	Ore mineral	Tetrahedrite	Accessory mineral (<1%)
	Ore mineral	Meneghinite	Accessory mineral (<1%)
	Ore mineral	Antimony	Accessory mineral (<1%)
	Ore mineral	Silver	Accessory mineral (<1%)

Lithology:

	Relationship	Rock	Origin
	Unknown	Grey gneiss with garnet	Extrusive Original rock :Tuff
			Metamorphic facies :Amphibolite
	Unknown	K-omvandlede bgt.er	Extrusive Original rock :Basalt
			Metamorphic facies :Amphibolite
	Unknown	Hornblende gneiss	Extrusive Original rock :Tuff
			Metamorphic facies :Amphibolite

Structures

	Location:	Type:	Orientation(360 gr.):	Relation to min.:
	Unknown	Mineral lineation	Strike :87	Post-mineralisation ;...Effect :Controls
	Unknown	Shear plane		Post-mineralisation ;...Effect :Modifies
	Unknown	Fold axis		Post-mineralisation ;...Effect :Controls

Information(s) in free text format

Free text

The Mofjellet deposit produced 4.35 Mt of ore with average grades of 3.61 % Zn, 0.71 % Pb and 0.31 % Cu in the period 1928–1987. The average silver and gold contents in the mainly semi-massive ore were around 10 and 0.3 ppm, respectively. However, in the last years before the mine was closed down, high gold grades were found during diamond drilling (2-12 ppm). The deposit consists of three ruler-shaped ore lenses situated more or less on top of each other. The ore lenses have a maximum width of about 100 meters. The lenses are connected through tight fold structures, where also gold is mainly concentrated. The total strike length of the deposit is more than 4 km. The deposit is hosted by a sequence of felsic and mafic volcanics, as well as metasediments (greywackes), formed in an arc/back-arc setting.

Bibliography:

From NGU's Reference Archive:

Bjerkgård, T.; Marker, M.; Sandstad, J.S.; Cook, N.J.; Sørdahl, T. , 2001

	Ore potential with emphasis on gold in the Mofjellet deposit, Rana, Nordland, Norway

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.2001.050;24 pages

Bjerkgård, Terje ; Marker, Mogens ; Gagama, Margrete Vik , 2006

	The Mofjellet Mine: Results of diamond drilling 2005

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.2006.058;31 s. pages

Abstract:

The report presents the results of diamond drilling carried out by MoMin AS in the Mofjellet Mine in 2005, and also some reinterpretation of older data. Twelve boreholes were drilled in 2005, distributed in three profiles, with the main target to further define an economic gold-rich mineralization related to the main sulfide ore bodies. The most interesting results from the work in 2005 were found in the western half of the deposit, where drilling in profile 43480Y revealed a possible gold-rich sulfide zone following the AKP structure, about 70-80 m long and 1-3 m wide containing on average 4,4% Cu+Pb+Zn, 20 ppm Ag and 0.9 ppm Au. More work is recommended in this area by drilling short holes from an old reailway tunnel. Interpretation of old data from the westernmost 800 m of the deposit show average grades of 3% Cu+Pb+Zn, 21 ppm Ag and 0.9 ppm Au over an average thickness of nearly 3 m. More work, including further interpretation of old data, structural geology and drilling is highly recommended in this part of the deposit to define economic resources,

Cook, Nigel J. , 2001

	Ore mineralogical investigation of the Mofjell deposit (Mo i Rana, Nordland, Norway) with emphasis on gold and silver distribution

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.2001.051;31 pages

Bjerkgård, Terje; Marker, Mogens; Slagstad, Trond; Solli, Arne , 2013

	The Mofjell project: summary and conclusions

;Norges geologiske undersøkelse;RAPPORT;NGU-rapport; No.2013.048;87 pages

Abstract:

The Mofjell project commenced in 2008 as a cooperation between GEXCO Norge AS, the county administration of Nordland and NGU. As GEXCO faced financial difficulties the external funding ended in 2009. The project area included Mofjellet and the eastern part of Plurdalen, an area with a large potential for economic sulfide deposits with Zn, Cu, Pb, Ag and Au. NGU has focused on establishing the geological setting of the Mofjell Group and its relation to ore formation. Another very important goal has been to assess the potential for economic ore deposits in the area, including enrichment of precious metals. On the basis of lithological observations and geochemistry, the Mofjell Group consists of a largely bimodal volcanic-sedimentary assemblage formed in an island-arc to back-arc setting. The data also show that the proportion of felsic volcanic rocks is much higher than previously described. A bimodal volcanic suite mixed with sediments is a geological environment which is regarded as favorable for both rich and large sulfide deposits.

Fangel, H. , 1959

	Uredning ang. langsiktig drift av Mofjellet Gruber og Andfiskåga flotasjonsverk.

;Norges geologiske undersøkelse;FAGRAPPORT;Bergarkivet; No.BA 7403;12 pages

	Abstract:
	Resultatene av innsatsen for å effektivisere diften, bedre utnyttelse av råmalmen og for å oppnå billigere produksjon er fremlagt. Vanskeligheter med ugunstig malmforløp mot vest og uheldige konjunkturer er også beskrevet. Til slutt er planene for åpning av malmfeltet mot øst lagt fram.

Dalsegg, Einar , 1984

	Turammålinger i Mofjellet, Mo i Rana, Nordland

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.84.168;21 pages

Singsaas, Per , 1961

	Geofysiske forsøksmålinger Mofjellet Gruber.

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.285;9 pages

Saager, R. , 1967

	Drei typen von Kieslagerstätten om Mofjell-Gebiet, Nordland, und ein neuer vorschlag zur gliederung der kaledonischen kieslager Norwegens

;Norsk geologisk forening;TIDSSKRIFTARTIKKEL;Norsk geologisk tidsskrift; No.47 (4);333-358 pages

Abstract:

Recent detailed investigations on Palaeozoic sulphide ore bodies in the Mofjell area, south of Mo i Rana (lat. 66°20'N) in northern Norway, revealed three different types of deposits. All these ore bodies lie in highly metamorphosed rocks of the Nordland facies above the Rødingsfjell thrust plane. The Mofjell-type deposits are banded pyritic zinc-lead ores while the Tretthammern-type deposits are less regular and poorly banded pyrrhotitic copperzinc ores. It is believed that the ores of both the above types are pre-metamorphic and have been formed by submarine hydrothermal solutions (initial magmatism of the Caledonan orogenesis) during the deposition of the sediments in the geosyncline. They can thus be regarded as of the exhalative-sedimentary type. The Hauknestind-type deposits are epigenetic pyrrhotitic zinc-lead replacement ores in marble layers and tectonic breccia zones. The ore-forming materials of these deposits probably originated from primary syngenetic sulphide ores, mobilized and emplaced in their present position during the later stage of the orogenesis. Based on this regional division in the Mofjell area, a new non-genetic, description classification of the sulphide ore bodies in the Caledonian mountain chain of Norway is proposed. The pyrite-type, consists dominantly of banded pyritic ores, and the mixed pyrite-pyrrhotite-typw, having a somewhat less distinct banding, consists of pyrite and pyrrhotite in equal amounts. The Cu-pyrrhotite-type contains irregular pyrrhotite-sphalerite ores while finally, the Zn-pyrrhotite-type is made up of pyrrhotite-sphalerite ores, which show a breccia texture. Comparison with the groups introduced by Stanton and Vokes show that the new classification is more comprehensive and does not include the discrepancies of the genetic differences in the Carstens-Foslie classes.

Bjørlykke, H. , 1951

	Rapport over geologiske undersøkelser ved Mofjellet gruber, sommeren 1951.

;Norges geologiske undersøkelse;FAGRAPPORT;Bergarkivet; No.BA 6461;33 pages

Abstract:

Det er foretatt befaringer av tilgjengelige deler av gruva og i dagen. Detaljerte dagboknotater fra 7/8 - 13/8 1950 og 18/6 - 21/6 1951 er vedlagt. Bergartene i området består av glimmerskifer og marmor med underordnete lag av amfibolitt. De er intrudert av granittiske lagerganger og gjennomskjærende ganger. De malmførende løsningene er antatt å være knyttet til den granittiske smelten. Malmen opptrer i tre linser eller soner; massiv impregnasjonsmalm i marmor og "stripet" malm paralellt skifrigheten i glimmerskiferen. De vigtigste malmmineraler er sinkbkende, svovelkis, blyglans og kobberkis. I mindre mengder finnes magnetkis, molybdenglans og vismutglans. Bergartene er sterkt foldet og overskyvninger er vanlig. Nøyaktig geologisk kartlegging og diamantboring fra feltort anbefales. Lister over innsamlete bergartsprøver med slip og analyser fra borkjerneprøver er vedlagt.

References not to be found in NGU's Reference Archive.:

Marker, M. og Mohr, Chr., 1974: Vestre Mofjellet: Strukturgeologiske træk fra kortbladene Langnes, Svabo, Hammeren og Kjempeheia. Int. rapp. Mofjellet Gruber.

Marker, M. 1976: Mofjell: Kortbladet Langnes. Strukturgeologiske træk fra kortbladet Langnees og vestlige del av kortbladet Svabo. Int. rapp. Mofjellet Gruber.

Kruse, A. 1964: Oversikt over malmfelt og malmletingsarbeider i Ranen (+Mosbergvik). Int. rapp. Mofjellet Gruber.

Kruse, A. og Burman, S. 1987: Gull og sølv i Mofjellet Gruber. Int. rapp. Mofjellet Gruber.

Saager, R. 1966: Erzgeologische Untersuchungen an Kaledonischen Blei, Zink und Kupfer fürenden Kieslagerstätten im Nord-Rana Distrikt, Nordnorwegen. (Mit besonderer berücksichtung der Mofjell Grube bei Mo i Rana). Prom. nr. 3732, City-Druck AG,Zürich

Spross, W. 1956: Bericht über die Untersuchungsarbeiten im Sommer 1956. Int. rapp. Mofjellet Gruber.

Kruse, A. 1979: "Geology and ore deposits of the area around Mo i Rana, N. Norway" in IGCP Project No. 60: Symposium on Caledonian - Appalachian Stratabound Sulphides. Guide Book for Pre-symposium excursion to Caledonian Ore Deposits in Norway and Sweden

Fieldsamples

	Sample No.	Sample type	Miscellanrous
	DH531 17.2-19.0 M	Core	Stored: Løkken Comment: Calc-silicate bearing gneiss with semi-massive sphalerite-galena ore. Subordinate chalcopyrite. No. of registrated element analyses = 1
	DH536 5.1-10.25 M	Core	Stored: Løkken Comment: Impregnation and semimassive sphalerite, galena, chalcopyrite and pyrite in muscovite-biotite gneiss, partly with calc-silicates No. of registrated element analyses = 1
	DH631 1.8-7.0 M	Core	Stored: Løkken Comment: Hornblende and calc-silicate bearing biotite gneiss with impregnation of sphalerite, chalcopyrite, galena and pyrite, at places semimassive. No. of registrated element analyses = 1
	DH7005.0.0-2.2 M	Core	Stored: Løkken/...Size(kg): 3 Comment: Rich impregnation of pyrite, sphalerite, galena in muscovite-biotite gneiss, subordinate chalcopyrite No. of registrated element analyses = 1
	DH7101 268.9-294 M	Core	Stored: Løkken Comment: Biotite-muscovite gneiss, partly skarn bearing. Varying impregnation to semimassive sphalerite, galena, chalcopyrite, pyrite mineralization No. of registrated element analyses = 1
	DH7604 253-254.75 M	Core	Stored: Løkken Comment: Hornblende-bearing biotite gneiss with rich impregnation to semimassive sphalerite with subordinate galena, chalcopyrite, pyrrhotite and pyrite. No. of registrated element analyses = 1
	NO0655.01	Bedrock	Sampler: Poulsen, T./...Stored: Løkken Comment: Diss. py-sl-malm. Impregnasjonsmalm i glimmerrik bergart med mer gneisøse partier imellom. Fra linse II eller III (?), 41840V
	NO0655.02	Bedrock	Sampler: Poulsen, T./...Stored: Løkken Comment: Diss. - semimassiv py+-sl-malm i biotittrik kyanittholdig skifer/gneis. I små linser ses konsentrasjoner av gult forvitrende py(?) og mye grovkrystallin sl. Linse III, 43600V
	NO0655.03	Bedrock	Sampler: Poulsen, T./...Stored: Løkken Comment: Semimassiv py-sl-malm i hornblende-biotitt-holdig skifer/gneis. Malmen synes svakt båndet i stor skala. Linse II eller III, 44200V
	NO0655.04	Bedrock	Sampler: Poulsen, T./...Stored: Løkken Comment: Semimassiv-massiv sl-py-malm i biotittrik gneis. Linse II, 44200V
	NO0655.05	Bedrock	Sampler: Poulsen, T./...Stored: Løkken Comment: Båndet semimassiv-massiv sl-py-ga-malm i kvarts(+feltspat)båndet (dm-størrelse) toglimmergneis. I kvarts(+feltspat)slirer ses grovkornet ga (mobilisert?) Linse II, 43660V

NB! All analyse values are shown at the end of the printout.:

Name of Sample point: Finnsete

(Object Id: 36729 76,00,01)

Location

County:

Nordland

Municipality:

Rana (1833)

Map 1:50000:

Mo i Rana (1927-1)

Map 1:250000:

Mo i Rana

Coordinate system:

EU89-UTM Zone 33

East:

461595 m.

North:

7353779 m.

Longitude:

14.1436820

Latitude:

66.3015040

Show on map

Resource

	Resource Type:	Base metals (Cu,Zn,Pb,Fe sulphides, As,Sb,Bi,Sn)	Resource Subtype:	Zinc
			Element(s):	Zn Pb Cu Kis

Information(s) in free text format

Free text

Stollinngang, nå gjenmurt. Antakelig opprinnelig Finnsete skjerp.

Fieldsamples

	Sample No.	Sample type	Miscellanrous
	MOFJ-1	Bedrock	Sampler: T. Bjerkgård/...Stored: Løkken Comment: Semimassive py-sl-ga ore from adit opening No. of registrated element analyses = 1

NB! All analyse values are shown at the end of the printout.:

Name of Locality: Skistua

(Object Id: 36728 76,01,00)

Location

County:

Nordland

Municipality:

Rana (1833)

Map 1:50000:

Storforshei (2027-4)

Map 1:250000:

Mo i Rana

Coordinate system:

EU89-UTM Zone 33

East:

465357 m.

North:

7353809 m.

Longitude:

14.2275450

Latitude:

66.3022120

Show on map

Resource

	Resource Type:	Base metals (Cu,Zn,Pb,Fe sulphides, As,Sb,Bi,Sn)	Resource Subtype:	Zinc
			Element(s):	Zn Pb Cu Kis

Resources and production

	Activity:	Pitting	Reserves:
	Operating method:		Historical production:

Information(s) in free text format

Free text

Gjengrodd røsk, 2 m lang og 1m dyp. Noen få blokker å finne.

Fieldsamples

	Sample No.	Sample type	Miscellanrous
	SKISTUA-01	Dump	Sampler: T. Bjerkgård Comment: py-sl-ga impregnation in biotite-muscovite gneiss No. of registrated element analyses = 1

NB! All analyse values are shown at the end of the printout.:

---

Analyse Results

from

Deposit Area 1833 - 076 Mofjellet

Element analyses

( *=parts pr. million, #=parts pr.billion, Negative values means below detection limit value.)

Sample No.	Sample Type	Cu*	Zn*	Pb*	Co*	Ni*	Ag*	Au#
DH531 17.2-19.0 M	Core	3554	141272	15361	10	35	9.0	48.0
DH536 5.1-10.25 M	Core	3289	34403	7314	8	20	12.0	159.0
DH631 1.8-7.0 M	Core	3321	41741	11694	20	18	17.5	349.0
DH7005.0.0-2.2 M	Core	3564	27391	5935	11	18	8.9	283.0
DH7101 268.9-294 M	Core	4084	34883	6128	11	18	10.9	197.0
DH7604 253-254.75 M	Core	3687	58576	7432	19	20	13.1	173.0
MOFJ-1	Bedrock	247	186500	20600	7	32	11.1	49.0
SKISTUA-01	Dump	3910	30800	8750	22	21	11.0	440.0

------------------

Sample No.	Pt#	Pd#	As*	Cd*	Ba*	Mo*	Sn*	Sb*	Bi*
DH531 17.2-19.0 M	2.0	2.0	17	603.1	51	61.00		12	14
DH536 5.1-10.25 M	2.0	5.0	13	148.1	23	18.00		9	6
DH631 1.8-7.0 M	2.0	2.0	7	175.8	9	41.00		11	6
DH7005.0.0-2.2 M	-2.0	2.0	13	134.5	30	37.00		11	5
DH7101 268.9-294 M	3.0	2.0	10	152.3	28	30.00		12	7
DH7604 253-254.75 M	2.0	4.0	13	279.0	29	18.00		7	2
MOFJ-1	10.0	5.0	7	760.0	645	283.00	-1	18	9
SKISTUA-01			-5		99700	88.00	1	14	15

------------------

Sample No.	Se*	Ga*	Ge*	In*	V*	Cr*	Mn*	Fe%	Th*
DH531 17.2-19.0 M							505
DH536 5.1-10.25 M							459
DH631 1.8-7.0 M							347
DH7005.0.0-2.2 M							653
DH7101 268.9-294 M							479
DH7604 253-254.75 M							942
MOFJ-1	27.00	21.00	-1.00	2.00	89	66	695	9.73	-1.00
SKISTUA-01		13.00						6.87

------------------

Sample No.	U*	W*	Rb*	Sr*	Y*	Zr*	Nb*	Ta*	La*
DH531 17.2-19.0 M
DH536 5.1-10.25 M
DH631 1.8-7.0 M
DH7005.0.0-2.2 M
DH7101 268.9-294 M
DH7604 253-254.75 M
MOFJ-1	10.00	5	10.0	149.0	7.0	7	-1.00	-1.00	-1.00
SKISTUA-01

------------------

Sample No.	Ce*	Sc*	Ti*	Te*	Hf*	Re*
DH531 17.2-19.0 M
DH536 5.1-10.25 M
DH631 1.8-7.0 M
DH7005.0.0-2.2 M
DH7101 268.9-294 M
DH7604 253-254.75 M
MOFJ-1	2.00	3.00	300	7.00	-1.00	-1
SKISTUA-01

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The fact sheet was created on 28.04.2024

Questions or comments regarding the fact sheet can be emailed to: ressursdatabaser@ngu.no

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