Norsk versjon
	THE ORE DATABASE
	Deposit Area 1740 - 005
	(Last updated 26.nov.1998)

Importance

Public:

Not Assessed (reg. 18.02.2015)

Economical:

Not classified/evaluated

Operations

	From - To	Activity	Comments
	1974 - 1974	Geophysics	Company/Institution :Elkem A/S
	1976 - 1976	Geology	Company/Institution :Elkem A/S
	1991 - 1991	Sampling	Company/Institution :NGU
	1995 - 1995	Inspection	Company/Institution :NGU

Mineralization

	Era:	Paleozoic	Period:	Ordovician
	Dating:		Method:
	Genesis:	Volcex	Form:	Layer
	Main texture:	Structureless	Min. distribution:	Massive (>50 % ore minerals)

Main grain size:

Fine grained (< 1 mm)

Main alteration:

Chloritisation

	Strike/Dip:	22 / 20	Direction:
			Plunge:

Stratigraphic classification of host rock

Era:

Paleozoic

Period:

	Province:	Caledonides
	Geotec.unit:	Køli Nappe Complex
	Tectonic complex:	Gjersvik Nappe
	Igneous complex:

Group:

Gjersvik

Formation:

Mineralogy

	Relationship	Mineral	Amount
	Gangue mineral	Quartz	Major mineral (>10%)
	Gangue mineral	Chlorite	Subordinate mineral (1-10%)
	Ore mineral	Pyrite	Major mineral (>10%)
	Ore mineral	Magnetite	Major mineral (>10%)
	Ore mineral	Pyrrhotite	Major mineral (>10%)
	Ore mineral	Chalcopyrite	Accessory mineral (<1%)

Lithology:

	Relationship	Rock	Origin
	Host rock	Chert	Sedimentary Original rock :Exhalite
			Metamorphic facies :Greenschist
	Wall rock	Greenstone	Extrusive Original rock :Basalt
			Metamorphic facies :Greenschist
	Wall rock	Quartz keratophyre	Extrusive Original rock :Tuff
			Metamorphic facies :Greenschist

Structures

	Location:	Type:	Orientation(360 gr.):	Relation to min.:
	Host rock	Primary layering	Strike/Dip :22 / 20	Syn-mineralisation ;...Effect :Controls

Information(s) in free text format

Free text

En rekke skjerp ligger rundt det øverste Nesåvatnet, Drikkevatnet, 3-4 km rett syd for Skorovatn. I nordenden av øverste Nesåvatnet ligger skjerpene A-C, mens D-F ligger langs sørenden av det samme vannet. Terrenget er åpent, og mineraliseringene er lett å finne. Det største C, Finnkjerringhullet, er valgt som hovedforekomsten. Ved C er det gjort betydelig skjerping, og kraftig rustdannelse preger terrenget rundt. Skjerpene nord for vannet ligger langs tre tilnærmet parallelle, N-S orienterte elektriske ledere mens skjerpene sør for vannet er tilknyttet en tilnærmet Ø-V orientert sone med elektriske ledere. Finnkjerringhullet C, ligger i forlengelsen av Skorovass forekomsten mot sør. Det er flere skjerp på den samme sonen. Tilnærmet flattliggende, massiv pyritt-malm som er minst 1 m mektig ligger i grågrønn, andesittisk metabasalt som dels er klorittisert. Innholdet av basemetaller er lavt. A og B er et svært små skjerp. I A finnes svak sulfiddisseminasjon og pyritt i smale striper med lokal kobberanrikning i kvartskeratofyr.B er en typisk vasskis, med 10 cm mektig, massiv pyritt sammen jaspis. D,E og F ligger langs en tilnærmet sammenhengende ekshalitthorisont som består av pyritt, magnetitt og chert med varierende mengdeforhold. Chert er dels magnetittrik; blåkvartsitt. Lengst i øst dominerer magnetkis med spor av kobberkis. Sona er opptil flere titalls meter mektig og består da hovedsakelig av chert. Lagene med massiv pyritt eller massiv magnetitt er mindre enn 1 m mektige. Grønnstein opptrer på begge sider av ekshalitten, men den er i nær kontakt med felsisk vulkanitt i tektonostratigrafisk heng i vest.

Bibliography:

From NGU's Reference Archive:

Oftedahl, Christoffer , 1958

	Oversikt over Grongfeltets skjerp og malmforekomster.

;Norges geologiske undersøkelse;TIDSSKRIFTARTIKKEL;NGU; No.202;1-75 + fo pages

Abstract:

Ore occurences of the Grong area: In the period 1910-1918 a great number of ore occurences were discovered in the Grong area. The late state geologist Steinar Foslie mapped the area in the years 1922-1931. Foslie also mapped all claims and occurences and made special field investigations in a few cases. This book presents a survey of all occurences chiefly based on the field observations of Foslie. In addition the present author has done some field work in connection with the three large deposits, Joma, Skorovass, and Gjersvik. The map, Plate 1, shows the areal geology and the location of the occurrences, numbered from 1 to 131. the ore of the occurrences is chiefly pyrite. The larger occurrences also contain some chalcopyrite and sphalerite etc. and the smaller occurrences contain ither pure pyrite with some magnetite. The Joma deposit (No. 1), contains about 15.5 mill. tons of ore. The ore zone forms an arc and is situated within a thick series of greenstones (Fig. 1). The Skorovass mine (No. 2), contains about 7,5 mill. tons of ore. The deposit is situated in a greenstone complex (Fig. 7), and is immediately surrounded by asid tuffs of quartz keratophyric composition (Table 1).

Singsaas, Per , 1975

	Turammålinger Skorovas grubefelt.

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.1290;12 pages

Singsaas, Per , 1960

	Geofysisk rekognosering Nesåvatn, Skorovas.

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.245;3 pages

Fieldsamples

	Sample No.	Sample type	Miscellanrous
	LS91171	Bedrock	Sampler :Størseth, L.R. Comment :Massive pyrite+chalcopyrite ore. No. of registrated element analyses = 1
	LS91172	Bedrock	Sampler :Størseth, L.R. Comment :Pyrite-chalcopyrite grains i quartz vein. No. of registrated element analyses = 1

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

Name of Locality : A

(Object Id : 1740,005,01,00)

---

Location

County :

Nord-Trøndelag (17)

Municipality :

Namsskogan (1740)

Map 1:50000:

Skorovatn (1824-2)

Map 1:250000:

Grong

Marking point:

Longitude:

13.1125940

Latitude:

64.6163250

EU89-UTM Zone 33

(Coordinates IS confirmed)

X-coord:

409731 m.

Y-coord:

7167039 m.

Commodity

	Main Type:	Base metals (Cu,Zn,Pb,Fe sulphides, As,Sb,Bi,Sn)	Sub Type:	Copper
			Element(s):	Cu Kis

Production

	Activity:	Pitting	Reserves:
	Prod. method:		Production:
	Prod. status:		Volume of dump:

Fieldsamples

	Sample No.	Sample type	Miscellanrous
	JS95049	Bedrock	Sampler :Sandstad, J.S./...Stored :Løkken Comment :Pyrite+sphalerite veins/bands in altered keratophyre. No. of registrated element analyses = 1
	LS91169	Bedrock	Sampler :Størseth, L.R. Comment :Massive chalcopyrite rich pyritic ore. No. of registrated element analyses = 1
	LS91170	Bedrock	Sampler :Størseth, L.R. Comment :Massive pyrite ore. No. of registrated element analyses = 1

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

Name of Locality : B

(Object Id : 1740,005,02,00)

---

Location

County :

Nord-Trøndelag (17)

Municipality :

Namsskogan (1740)

Map 1:50000:

Skorovatn (1824-2)

Map 1:250000:

Grong

Marking point:

Longitude:

13.1200810

Latitude:

64.6139070

EU89-UTM Zone 33

(Coordinates IS confirmed)

X-coord:

410082 m.

Y-coord:

7166759 m.

Commodity

	Main Type:	Base metals (Cu,Zn,Pb,Fe sulphides, As,Sb,Bi,Sn)	Sub Type:	Copper
			Element(s):	Kis

Production

	Activity:	Pitting	Reserves:
	Prod. method:		Production:
	Prod. status:		Volume of dump:

Fieldsamples

	Sample No.	Sample type	Miscellanrous
	AR95176	Dump	Sampler :Reinsbakken, A./...Stored :Løkken Comment :Pyrite ore, massive, fine grained. No. of registrated element analyses = 1

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

Name of Locality : D

(Object Id : 1740,005,03,00)

---

Location

County :

Nord-Trøndelag (17)

Municipality :

Namsskogan (1740)

Map 1:50000:

Skorovatn (1824-2)

Map 1:250000:

Grong

Marking point:

Longitude:

13.0815100

Latitude:

64.6003950

EU89-UTM Zone 33

(Coordinates IS confirmed)

X-coord:

408192 m.

Y-coord:

7165309 m.

Commodity

	Main Type:	Base metals (Cu,Zn,Pb,Fe sulphides, As,Sb,Bi,Sn)	Sub Type:	Copper
			Element(s):	Kis

Production

	Activity:	Pitting	Reserves:
	Prod. method:		Production:
	Prod. status:		Volume of dump:

Fieldsamples

	Sample No.	Sample type	Miscellanrous
	JS95136	Block	Sampler :Sandstad, J.S./...Stored :Løkken Comment :Massive pyrrhotite and semi-massive pyrite with chlorite-rich matrix. No. of registrated element analyses = 1

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

Name of Locality : E

(Object Id : 1740,005,04,00)

---

Location

County :

Nord-Trøndelag (17)

Municipality :

Namsskogan (1740)

Map 1:50000:

Skorovatn (1824-2)

Map 1:250000:

Grong

Marking point:

Longitude:

13.0958310

Latitude:

64.6018370

EU89-UTM Zone 33

(Coordinates IS confirmed)

X-coord:

408881 m.

Y-coord:

7165449 m.

Commodity

	Main Type:	Base metals (Cu,Zn,Pb,Fe sulphides, As,Sb,Bi,Sn)	Sub Type:	Copper
			Element(s):	Kis

Production

	Activity:	Pitting	Reserves:
	Prod. method:		Production:
	Prod. status:		Volume of dump:

Structures

	Location:	Type:	Orientation(360 gr.):	Relation to min.:
	Host rock	Foliation	Strike/Dip :85 / 30	Post-mineralisation ;...Effect :Modifies

Information(s) in free text format

Free text

Vekslende lag med chert, dels magnetittførende ('blåkvarts'), massiv sulfid og massiv magnetitt finnes på begge sider av et mindre dalsøkk. Ekshalittsonen dominers av chert er tilsynelatende få titalls meter mektig

Fieldsamples

	Sample No.	Sample type	Miscellanrous
	JS95135	Bedrock	Sampler :Sandstad, J.S./...Stored :Løkken Comment :Pyrite+pyrrhotite veins (cm scale) in white chert/altered felsic volcanite. No. of registrated element analyses = 1
	LS91173	Bedrock	Sampler :Størseth, L.R. Comment :Banded fine grained pyrite ore ('vasskis'). No. of registrated element analyses = 1

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

Name of Sample point : E

(Object Id : 1740,005,04,01)

---

Location

County :

Nord-Trøndelag (17)

Municipality :

Namsskogan (1740)

Map 1:50000:

Skorovatn (1824-2)

Map 1:250000:

Grong

Marking point:

Longitude:

13.0937990

Latitude:

64.6010030

EU89-UTM Zone 33

(Coordinates IS confirmed)

X-coord:

408781 m.

Y-coord:

7165359 m.

Commodity

	Main Type:	Base metals (Cu,Zn,Pb,Fe sulphides, As,Sb,Bi,Sn)	Sub Type:	Copper
			Element(s):	Cu Kis

Fieldsamples

	Sample No.	Sample type	Miscellanrous
	JS95133	Bedrock	Sampler :Sandstad, J.S./...Stored :Løkken Comment :Massive pyrite ore, fine grained, magnetite laminae. No. of registrated element analyses = 1
	JS95134	Bedrock	Sampler :Sandstad, J.S./...Stored :Løkken Comment :Massive magnetite, fine grained, brownish black. No. of registrated element analyses = 1

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

Name of Locality : F

(Object Id : 1740,005,05,00)

---

Location

County :

Nord-Trøndelag (17)

Municipality :

Namsskogan (1740)

Map 1:50000:

Skorovatn (1824-2)

Map 1:250000:

Grong

Marking point:

Longitude:

13.1084860

Latitude:

64.6002040

EU89-UTM Zone 33

(Coordinates IS confirmed)

X-coord:

409481 m.

Y-coord:

7165249 m.

Commodity

	Main Type:	Base metals (Cu,Zn,Pb,Fe sulphides, As,Sb,Bi,Sn)	Sub Type:	Copper
			Element(s):	Kis

Production

	Activity:	Pitting	Reserves:
	Prod. method:		Production:
	Prod. status:		Volume of dump:

Information(s) in free text format

Free text

Det største skjerpet i området på sørsida av det Øverste Nesåvatnet finnes på et lite nes i østkanten av et mindre vann. Det består av en 2 mlang og 2 m høy skjæring i svært forvitra bergarter, men i skjerpet finnes mange blokker med massiv sulfid. Ekshalittsonen bestå i tillegg av fint båndet chert/blåkvarts, pyritt og magnetitt.

Fieldsamples

	Sample No.	Sample type	Miscellanrous
	JS95130	Bedrock	Sampler :Sandstad, J.S./...Stored :Løkken Comment :Massive pyrrhotite, few chert lenses. No. of registrated element analyses = 1
	JS95131	Bedrock	Sampler :Sandstad, J.S/...Stored :Løkken Comment :Pyrite aggregates in weathered, white chert. No. of registrated element analyses = 1
	JS95132	Bedrock	Sampler :Sandstad, J.S./...Stored :Løkken Comment :Magnetite rich, dark bluish chert ('blue quartzite'). No. of registrated element analyses = 1
	LS91174	Bedrock	Sampler :Størseth, L.R. Comment :Fine grained, massive pyrite ore ('vasskis'). No. of registrated element analyses = 1

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

---

Analyse Results

from

Deposit Area 1740 - 005 Øverste Nesåvatnet

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#
AR95176	Dump	347	260	27	7	26	.7	67.0
JS95049	Bedrock	465	1878	22	40	8	3.3	82.0
JS95130	Bedrock	434	1359	34	-1	95	-.3	10.0
JS95131	Bedrock	51	18	-3	3	7	-.3	-2.0
JS95132	Bedrock	32	5	3	-1	5	-.3	6.0
JS95133	Bedrock	148	123	39	1	36	.7	61.0
JS95134	Bedrock	99	208	-3	1	24	.5	4.0
JS95135	Bedrock	64	39	18	2	27	1.6	109.0
JS95136	Block	256	207	12	31	65	.6	49.0
LS91169	Bedrock	99999	869	25	438	7	21.3	331.0
LS91170	Bedrock	9002	94	33	152	7	2.0	86.0
LS91171	Bedrock	5578	1486	156	23	6	1.8	146.0
LS91172	Bedrock	939	540	6	12	14	.3	6.0
LS91173	Bedrock	419	395	82	6	35	.9	42.0
LS91174	Bedrock	134	55	24	8	48	.8	61.0

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

Sample No.	Pt#	Pd#	As*	Cd*	Ba*	Mo*	Sb*	Bi*	S%
AR95176	3.0	-3.0	142	2.5	5	2.00	5	-2	32.79
JS95049	-3.0	-3.0	187	2.8	7	9.00	7	-2	14.90
JS95130	-3.0	-3.0	43	4.5	5	4.00	10	-2	31.27
JS95131	-3.0	-3.0	43	-.2	2	5.00	3	3	2.10
JS95132	-3.0	-3.0	223	-.2	3	4.00	2	-2	3.43
JS95133	-3.0	-3.0	143	1.2	4	7.00	2	-2	27.06
JS95134	10.0	6.0	17	1.2	119	-1.00	-2	-2	.75
JS95135	-3.0	-3.0	110	.2	5	24.00	5	-2	19.82
JS95136	-3.0	4.0	40	1.3	9	9.00	-2	-2	29.66
LS91169	1.0	1.0	166	14.4	3	1.00	2	3	31.34
LS91170	1.0	1.0	83	.3	2	1.00	2	21	34.66
LS91171	1.0	2.0	137	2.6	6	3.00	9	7	37.10
LS91172	1.0	2.0	11	1.3	4	4.00	2	2	1.48
LS91173	1.0	5.0	128	1.6	4	1.00	2	2	37.20
LS91174	5.0	7.0	102	.4	6	9.00	5	2	31.34

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

Sample No.	V*	Cr*	Mn*	Fe%	Th*	U*	W*	Sr*	La*
AR95176	69	21	1733	25.65	2.00	5.00	-2	3.0	5.00
JS95049	40	5	753	18.75	-2.00	-5.00	-2	-1.0	1.00
JS95130	15	7	120	43.04	2.00	6.00	-2	5.0	5.00
JS95131	10	5	59	3.44	-2.00	-5.00	-2	5.0	-1.00
JS95132	4	5	52	6.18	-2.00	-5.00	-2	5.0	1.00
JS95133	64	12	2700	25.55	-2.00	-5.00	-2	9.0	3.00
JS95134	87	21	6312	26.10	2.00	-5.00	-2	46.0	20.00
JS95135	78	15	613	22.43	-2.00	-5.00	-2	14.0	1.00
JS95136	78	17	610	39.61	2.00	7.00	-2	21.0	2.00
LS91169	53	37	365	38.31	1.00	5.00	2	1.0	2.00
LS91170	68	19	622	34.49	1.00	5.00	1	1.0	2.00
LS91171	19	28	381	22.09	1.00	5.00	1	23.0	2.00
LS91172	10	18	413	2.73	1.00	5.00	1	15.0	2.00
LS91173	74	30	388	22.47	2.00	5.00	1	2.0	2.00
LS91174	56	24	972	31.67	1.00	5.00	1	3.0	2.00

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

Sample No.	B*
AR95176	3
JS95049	3
JS95130	-3
JS95131	-3
JS95132	3
JS95133	-3
JS95134	-3
JS95135	-3
JS95136	-3
LS91169	5
LS91170	5
LS91171	3
LS91172	2
LS91173	3
LS91174	6

---

The fact sheet was created on 20.01.2025

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

Copyright © 2025 Geological Survey of Norway