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THE ORE DATABASE
Deposit Area 439 - 012
(Last updated 26.okt.2023)

Name of Deposit Area : Nordre Geitryggen
(Object Id : 0439,012,00,00)
Location
County : Hedmark (04) Municipality : Folldal (0439)
Map 1:50000: Folldal (1519-2) Map 1:250000: Røros
Marking point: Longitude: 10.0877220 Latitude: 62.1508500
EU89-UTM Zone 32 (Coordinates IS confirmed)
X-coord: 556688 m. Y-coord: 6891460 m.
Commodity
Main Type: Base metals (Cu,Zn,Pb,Fe sulphides, As,Sb,Bi,Sn) Sub Type: Zinc
Element(s): Kis Zn Cu
Production
Activity: Mining Reserves:
Prod. method: Underground mining Production: 2500 thousand tons
Prod. status: Disused, closed Volume of dump: 0 m3

Importance
Public: Little Importance (reg. 18.02.2015)
Economical: Minor interest

Products
Element/product Crude ore grade or quality
AG 31 ppm
AU 0.27 ppm
CU 1.6 %
PB 0.3 %
ZN 4.5 %

Operations
From - To Activity Comments
1919 - 1919 Core drilling Company/Institution :The Foldal Copper and Sulphur ltd.
1920 - 1926 Test mining Company/Institution :The Foldal Copper and Sulphur ltd.
1923 - 1923 Core drilling Company/Institution :The Foldal Copper and Sulphur ltd.
1931 - 1935 Test mining Company/Institution :The Foldal Copper and Sulphur ltd.
1935 - 1938 Regular production Company/Institution :The Foldal Copper and Sulphur ltd.
1938 - 1970 Regular production Company/Institution :Folldal Verk A/S
1941 - 1941 Core drilling Company/Institution :Folldal Verk A/S
1941 - 1941 Geophysics Company/Institution :Geofysisk Malmleting
1990 - 1993 Detail mapping Company/Institution :T. Bjerkgård, University of Oslo

Mineralization
Era: Paleozoic Period: Ordovician
Dating: Method:
Genesis: Volcex Form: Lens
Main texture: Banded Min. distribution: Massive (>50 % ore minerals)
Main grain size: Medium grained (1-3 mm) Main alteration: Chloritisation
Strike/Dip: 222 / 40 Direction: 45
Plunge: 45
Stratigraphic classification of host rock
Era: Paleozoic Period: Ordovician
Province: Caledonides
Geotec.unit: Trondheim Nappe Complex
Tectonic complex: Meråker Nappe
Igneous complex:
Group: Fundsjø Formation:

Mineralogy
Relationship Mineral Amount
Gangue mineral Calcite Major mineral (>10%)
Gangue mineral Quartz Major mineral (>10%)
Gangue mineral Chlorite Subordinate mineral (1-10%)
Gangue mineral Clinoamphibole Subordinate mineral (1-10%)
Gangue mineral Biotite Accessory mineral (<1%)
Gangue mineral Titanite Accessory mineral (<1%)
Gangue mineral Muscovite Accessory mineral (<1%)
Gangue mineral Plagioclase Accessory mineral (<1%)
Gangue mineral Clinozoisite Accessory mineral (<1%)
Ore mineral Sphalerite Major mineral (>10%)
Ore mineral Pyrrhotite Major mineral (>10%)
Ore mineral Chalcopyrite Major mineral (>10%)
Ore mineral Pyrite Major mineral (>10%)
Ore mineral Magnetite Subordinate mineral (1-10%)
Ore mineral Galena Subordinate mineral (1-10%)
Ore mineral Tetrahedrite Accessory mineral (<1%)
Ore mineral Rutile Accessory mineral (<1%)
Ore mineral Cubanite Accessory mineral (<1%)
Ore mineral Stannite Accessory mineral (<1%)
Ore mineral Tellurobismuthite Accessory mineral (<1%)
Ore mineral Molybdenite Accessory mineral (<1%)
Ore mineral Hessite Accessory mineral (<1%)
Ore mineral Arsenopyrite Accessory mineral (<1%)
Ore mineral Marcasite Accessory mineral (<1%)

Lithology:
Relationship Rock Origin
Wall rock Chlorite schist Sedimentary
Original rock :Tuffite
Metamorphic facies :Greenschist
Wall rock Graphite schist
Metamorphic facies :Greenschist
Wall rock Quartz-albite-sericite schist Sedimentary
Original rock :Tuffite
Metamorphic facies :Greenschist
Wall rock Quartz keratophyre Extrusive
Original rock :Rhyodacite
Metamorphic facies :Greenschist

Structures
Location: Type: Orientation(360 gr.): Relation to min.:
Wall rock Foliation Strike/Dip :236 / 65 Post-mineralisation ;...Effect :Controls

Information(s) in free text format
Free text
The Nordre Geitryggen mine produced 2.5 mill.t. of ore with 1.3 % Cu, 3.2 % Zn, 0.2 % Pb, 31 ppm Ag og 0.2 ppm Au, mainly between 1936 and 1970, and was the largest of the Folldal mines. The deposit is situated in banded chlorite schists, which are typical tuffitic rocks in the area. Thin lenses of felsic volcanics and volcaniclastics are interbanded in the schists, as well as horizons of graphite schist. The ore zone has a strike length of 550 m, and was mined to a vertical depth of 550 m. The average ore thickness was 1.7 m, but varied between 0.1 and 10.4 m because of folding. The ore was generally a banded pyrite-sphalerite-pyrrhotite-chalcopyrite ore with local enrichments of magnetite. The matrix was dominated by calcite and quartz.

Bibliography:
From NGU's Reference Archive:
Riiber, C.C.; Aasgaard, Gunnar , 1935
Foldal. Beskrivelse til det geologiske rektangelkart. D. grubebeskrivelser. Beskrivelse av kis- og kobbergruber og skjerp i Foldal, Dovre og Alvdal herreder
;Norges geologiske undersøkelse;KARTBESKRIVELSE; TIDSSKRIFTARTIKKEL;NGU; No.145;68-69 pages

Marlow, Wolmer , 1935
Foldal. Beskrivelse til geologiske rektangelkart. D. Grubebeskrivelser. 1. Beskrivelse av Foldals kisfelt: 1. Foldals verks gruber. 2. Statens kisanvisninger. 3. Grimsboskjerpene. 4. Rødalens grube. 5. Tronfjellets grube. 6. Verkjensdalens kisfelt.
;Norges geologiske undersøkelse;KARTBESKRIVELSE; TIDSSKRIFTARTIKKEL;NGU; No.145;69-96 pages

Marlow, Wolmer , 1935
Foldal. Beskrivelse til det geologiske rektangelkart. D. Grubebeskrivelser. 4. Andre gruber og skjerp.
;Norges geologiske undersøkelse;KARTBESKRIVELSE; TIDSSKRIFTARTIKKEL;NGU; No.145;109 pages

Page, Norman J. , 1964
The sulphide deposit of Nordre Gjetryggen Gruve, Folldal, Norway.
;Norges geologiske undersøkelse;TIDSSKRIFTARTIKKEL;NGU; No.228;217-269 pages
Abstract:
Nordre Gjetryggen Gruve in the Folldal district, southern Norway, is at approximately 62 9'N. latitude and 10 E. longitude. The mining of copper from pyritic ores began in the area in 1748, while the recovery of zinc and sulphur became important in the 19th century, Nordre Gruve alone yielded 1,1 million metric tons of raw ore before 1957. From then until 1962 it produced about 65 thousand tons of raw ore per year. The mine has been developed for about 420 meters along the strike of N.42 E. and to a depth of 510 meters. The ore body dips 38 NW. in the western part and between 45-50 NW. in the eastern part; the ore zone plunges 45 NE. The average thickness of the ore is 1,66 meters. Geologically, the district is in the southwestern part of the Trondheim region near the Sparagmite boundary and Nordre Gruve can be cosidered to be on the southwest limb of a northeasterly plunging syncline composed of schists in the quartz-albite-epidote-almandine subfacies of the greenschist facies that have been assigned tentatively to rock units similar to those in the Hølonda-Horg district. The rock units mapped are: 1) undifferentiated schists composed dominantly of quartz, chlorite, calcite, biotite, epidote, and hornblende; 2) quartzite schists; 3) hornblende-quartz schist; and 4) trondhjemite now albite-quartz-garnet gneiss, and surficial material.

Bjerkgård, Terje , 1995
The stratabound massive sulfide deposits in the Folldal area, southern Trondheim region Caledonides, Norway.
;UiO Geologisk fellesråd;AVHANDLING

Bjerkgård, Terje; Bjørlykke, Arne , 1994
The stratabound sulphide deposits in the Folldal area, Southern Trondheim Region, Norway
;Norsk geologisk forening;TIDSSKRIFTARTIKKEL;Norsk geologisk tidsskrift; No.74 (4);213-237 pages
Abstract:
Frie emneord: Lagdelt, Malmgenese Five strata-bound massive sulphide deposits are situated at three different stratigraphic levels in the volcanogenic Fundsjø group in the Folldal area. The deposits are hosted in metabasalts, metarhyodacites and volcanoclastic rocks and belong to the Cu-Zn class of volcanic-associated massive sulphide deposits. The metal content of the deposits indicates that the sources of metals are underlying strata, possibly with a contribution from intrusives. Wall rock alteration varies according to differences in host rocks, and is probably a result of chemical variations of the host rocks, temperature differences and proximity to the hydrothermal vent. The clustering of deposits in the Folldal area is considered to be due to the occurrence of a large sub- volcanic trondhjemitic intrusion which acted as the major heat engine for convection. The small size of the deposits might be related to the shallow level of the intrusion.

Singsaas, Per , 1965
Geofysisk undersøkelse Nordøst for Hovedgruben. Sydøst for Nordre Gjetryggen Grube.
;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.552 B;6 pages

Singsaas, Per; Brækken, H. , 1941
Elektromagnetisk undersøkelse Nordre Gjetryggen Grube
;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.25;17 pages

References not to be found in NGU's Reference Archive.:
Per B. Støen 1948: Folldal Verk gjennom 200 år. Historiske trekk: 1748-1948. festskrift Folldal Verk A/S, 70 sider.


Bjerkgård, T. & Bjørlykke A.,1996: Sulfide deposits in Folldal, Southern Trondheim Region Caledonides, Norway: Source of metals and wall-rock alterations related to host rocks. Economic Geology vol.91, p.676-696.


Bjerkgård, T. & Bjørlykke, A. 1995: Geology of the Folldal area, southern Trondheim Region Caledonides, Norway. NGU bull. 426, p.53-75.


Heim, J.G. 1972: Zur geologie des Südlichen Trondheim-gebietes. Unpubl. Ph.D. thesis, Univ. Mainz, 156 pp.

Fieldsamples
Sample No. Sample type Miscellanrous
AVERAGE OF 25 SMPLS Core
Sampler :T. Bjerkgård
Comment :Average of 25 core analyses
No. of registrated element analyses = 1
DBH11-1 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH11-2 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH11-3 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH12-1 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH12-2 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH12-3 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH15-1 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH15-2 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH4-1 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH4-2 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH5-1 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH5-10 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH5-2 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH5-3 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH5-4 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH5-5 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH5-6 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH5-7 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH5-8 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH5-9 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH7-1 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH7-2 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH9-1 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH9-2 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
DBH9-3 Core
Sampler :T. Bjerkgård
No. of registrated element analyses = 1
NB! All analyse values are shown at the end of the printout.:

Analyse Results
from
Deposit Area 439 - 012 Nordre Geitryggen

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#
AVERAGE OF 25 SMPLS Core 16300 45100 3059 152 -100 31.0 273.0
DBH11-1 Core 16800 72600 5870 71 50 330.0
DBH11-2 Core 4500 77800 12800 9 50 120.0
DBH11-3 Core 10100 56800 4840 390 50 120.0
DBH12-1 Core 4020 93800 18300 71 50 89.0
DBH12-2 Core 31800 49700 4000 290 50 490.0
DBH12-3 Core 6410 49300 7130 72 50 230.0
DBH15-1 Core 10700 14800 2960 180 50 670.0
DBH15-2 Core 11000 25600 4710 190 50 180.0
DBH4-1 Core 11100 23400 344 52 50 220.0
DBH4-2 Core 23500 49600 4460 280 50 420.0
DBH5-1 Core 24500 14000 146 310 50 390.0
DBH5-10 Core 26000 11200 568 160 50 260.0
DBH5-2 Core 16900 59300 143 120 50 210.0
DBH5-3 Core 22300 8840 126 130 50 480.0
DBH5-4 Core 5470 78000 1480 3 50 90.0
DBH5-5 Core 9100 69700 3100 68 50 200.0
DBH5-6 Core 33300 25300 1200 150 50 400.0
DBH5-7 Core 34500 32700 524 130 50 430.0
DBH5-8 Core 12600 60000 6170 130 50 400.0
DBH5-9 Core 12100 92900 2060 95 50 270.0
DBH7-1 Core 10100 6400 161 120 50 71.0
DBH7-2 Core 9470 66200 5620 71 50 210.0
DBH9-1 Core 18300 43800 1690 480 50 260.0
DBH9-2 Core 36800 17600 646 330 50 330.0
DBH9-3 Core 17000 36500 1700 290 50 330.0
------------------
Sample No. As* Ba* Mo* Sn* Sb* Bi* Se* S% Cr*
AVERAGE OF 25 SMPLS 292 -100 24.00 -10 4 21 80.00 35.60 179
DBH11-1 650 28.00 9 21 70.00 150
DBH11-2 480 43.00 15 13 19.00 180
DBH11-3 200 17.00 3 47 160.00 160
DBH12-1 94 29.00 3 20 190.00 370
DBH12-2 130 41.00 1 20 130.00 270
DBH12-3 89 44.00 2 21 94.00 240
DBH15-1 33 13.00 1 21 44.00 230
DBH15-2 120 21.00 1 2 73.00 330
DBH4-1 230 20.00 8 62.00 110
DBH4-2 440 33.00 12 30 140.00 190
DBH5-1 130 7.00 1 6 110.00 200
DBH5-10 240 25.00 1 16 66.00 150
DBH5-2 160 10.00 0 8 72.00 200
DBH5-3 41 2.50 0 8 49.00 130
DBH5-4 150 14.00 1 15 28.00 190
DBH5-5 540 33.00 2 31 56.00 120
DBH5-6 250 15.00 1 32 69.00 160
DBH5-7 300 21.00 1 7 75.00 150
DBH5-8 600 25.00 3 71 71.00 160
DBH5-9 490 30.00 2 38 71.00 160
DBH7-1 83 13.00 8 73.00 160
DBH7-2 710 44.00 30 12 57.00 170
DBH9-1 250 21.00 22 99.00 210
DBH9-2 130 13.00 7 140.00 230
DBH9-3 200 37.00 32 120.00 190
------------------
Sample No. U* Rb*
AVERAGE OF 25 SMPLS 3.00
DBH11-1 2.00 15.0
DBH11-2 6.30 15.0
DBH11-3 0.90 30.0
DBH12-1 2.30 15.0
DBH12-2 3.50 15.0
DBH12-3 7.00 15.0
DBH15-1 1.80 15.0
DBH15-2 3.90 15.0
DBH4-1 2.20 15.0
DBH4-2 2.60 15.0
DBH5-1 0.90 15.0
DBH5-10 3.70 15.0
DBH5-2 1.40 15.0
DBH5-3 1.50 15.0
DBH5-4 1.60 15.0
DBH5-5 2.30 15.0
DBH5-6 2.70 15.0
DBH5-7 2.80 15.0
DBH5-8 3.20 15.0
DBH5-9 3.40 15.0
DBH7-1 1.20 15.0
DBH7-2 1.40 15.0
DBH9-1 1.20 15.0
DBH9-2 2.50 15.0
DBH9-3 2.60 15.0

The fact sheet was created on 03.12.2023
Questions or comments regarding the fact sheet can be emailed to:
ressursdatabaser@ngu.no
Copyright © 2023 Geological Survey of Norway