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	THE ???? DATABASE
	Occurence 0 - 000 FEIL
	(Object Id: ) (Last updated: 18.03.2024)

Products

	Element/product	Crude ore grade or quality	Reg. date
	Cu	1.3 %	01.02.2001
	Zn	3.2 %	01.02.2001

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
	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.:

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The fact sheet was created on 05.05.2024

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