Norsk versjon
	THE ORE DATABASE
	Deposit Area 1742 - 012
	(Last updated 16.okt.2001)

Importance

Public:

Not Assessed (reg. 18.02.2015)

Economical:

Not classified/evaluated

Operations

	From - To	Activity	Comments
	1971 - 1971	Sampling	Company/Institution :NGU
	1991 - 1991	Sampling	Company/Institution :NGU

Mineralization

	Era:	Paleozoic	Period:
	Dating:		Method:
	Genesis:	Volcex	Form:	Layer
	Main texture:	Structureless	Min. distribution:	Semi-massive (20-50 % ore minerals)

Main grain size:

Medium grained (1-3 mm)

Main alteration:

Error: Text missing

	Strike/Dip:		Direction:
			Plunge:

Stratigraphic classification of host rock

Era:

Paleozoic

Period:

	Province:	Caledonides
	Geotec.unit:	Trondheim Nappe Complex
	Tectonic complex:	Gula Nappe
	Igneous complex:

Group:

Formation:

Mineralogy

	Relationship	Mineral	Amount
	Gangue mineral	Quartz	Major mineral (>10%)
	Gangue mineral	Plagioclase	Major mineral (>10%)
	Gangue mineral	Biotite	Subordinate mineral (1-10%)
	Ore mineral	Pyrrhotite	Major mineral (>10%)
	Ore mineral	Pyrite	Major mineral (>10%)

Lithology:

	Relationship	Rock	Origin
	Wall rock	Keratophyre	Text missing Original rock :Text missing
			Metamorphic facies :Amphibolite
	Wall rock	Amphibolite	Extrusive Original rock :Text missing
			Metamorphic facies :Amphibolite

Structures

	Location:	Type:	Orientation(360 gr.):	Relation to min.:
	Host rock	Fold axis	Dir./Plunge :135 / 10	Post-mineralisation ;...Effect :Modifies

Information(s) in free text format

Free text

Forekomsten ligger i en skjæring i en skogsbilvei rett ovenfor jernbanebrua ved Fossland, 2,5 km fra Grong sentrum, kote 140. Mineraliseringen kan følges over 20 m i vegskjæringen og videre i vertikalretning i den bratte fjellveggen. Den består av svovelkis i massive bånd som er foldet og massiv til disseminert magnetkis i skifrig amfibolitt som er en slags sidebergart. Overgang til kvartskeratofyr sees i skjæringene mot nord. En dm-bred kvartsgang er noe sulfidmineralisert. Mineraliseringens orientering er ikke registrert. Tidligere skjerpearbeid antas å være tildekket av nyere vegfylling.

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).

Logn, Ø. , 1971

	Geologiske, geofysiske og geokjemiske undersøkelser Grongfeltet/Grongprosjektet.

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.905;12 pages

	Abstract:
	Under oppdrag 905 ble det utført undersøkelser på en rekke objekter. Det vises til NGU Rapport nr. 84.091: Statusrapport for geofysikk utført i Nord-Trøndelag fylke (1984).

Fieldsamples

	Sample No.	Sample type	Miscellanrous
	gr0101	Bedrock	Sampler :Sandstad, J.S. Comment :Fine grained quartz vein with med weak-moderate py-diss. No. of registrated element analyses = 1
	gr0102	Bedrock	Sampler :Sandstad, J.S. Comment :Fine grained quartz keratophyre with weak-moderate py-diss. No. of registrated element analyses = 1
	GR0103	Bedrock	Sampler :Sandstad, J.S. Comment :Pyrite ore, massive, fine grained, few quartz lenses. No. of registrated element analyses = 1
	gr0104	Bedrock	Sampler :Sandstad, J.S. Comment :Amphibolite with weak-moderate py-diss. No. of registrated element analyses = 1
	gr0105	Bedrock	Sampler :Sandstad, J.S. Comment :Weak py-diss. in fine grained, banded keratophyre. No. of registrated element analyses = 1
	LS91130	Bedrock	Sampler :Størseth, L.R. Comment :Massive py-po-ore. No. of registrated element analyses = 1
	LS91131	Bedrock	Sampler :Størseth, L.R. Comment :Massive po-ore. No. of registrated element analyses = 1
	LS91132	Bedrock	Sampler :Størseth, L.R. Comment :Massive py-po in qartz vein. No. of registrated element analyses = 1
	1150	Bedrock	No. of registrated element analyses = 1
	1151	Bedrock	No. of registrated element analyses = 1
	1152	Bedrock	No. of registrated element analyses = 1
	1153	Bedrock	No. of registrated element analyses = 1
	1154	Bedrock	No. of registrated element analyses = 1

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

---

Analyse Results

from

Deposit Area 1742 - 012 Medjåsfjellet

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#
gr0101	Bedrock	72	487	14	2	10	.1	7.0
gr0102	Bedrock	51	212	10	7	7	.1	5.0
GR0103	Bedrock	51	79	6	23	18	.1	26.0
gr0104	Bedrock	25	65	3	19	19	.1	3.0
gr0105	Bedrock	24	145	2	11	28	.1	1.0
LS91130	Bedrock	920	31	5	33	114	.8	8.0
LS91131	Bedrock	622	132	30	33	64	1.6	18.0
LS91132	Bedrock	215	52	4	30	51	.8	11.0
1150	Bedrock	31	349	5	4	17	.5	39.0
1151	Bedrock	44	325	4	5	19	.4	29.0
1152	Bedrock	195	282	4	5	26	.6	10.0
1153	Bedrock	458	53	4	2	82	1.2	11.0
1154	Bedrock	311	31	3	7	69	.8	16.0

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

Sample No.	Pt#	Pd#	As*	Cd*	Ba*	Mo*	Sb*	Bi*	S%
gr0101	1.0	1.0	34	1.6	8	8.00	2	2	.63
gr0102	1.0	2.0	19	.5	88	1.00	2	2	1.55
GR0103	9.0	15.0	116	.2	6	1.00	4	2	41.10
gr0104	1.0	5.0	7	.7	70	1.00	2	2	.29
gr0105	1.0	1.0	2	.2	248	1.00	2	2	.16
LS91130	2.0	3.0	81	.2	13	11.00	2	2	33.26
LS91131	1.0	5.0	31	1.1	8	6.00	2	2	17.96
LS91132	1.0	2.0	71	.2	4	4.00	2	2	27.41
1150	3.0	4.0	150	.2	7	1.00	2	2	32.78
1151	5.0	3.0	151	.2	6	2.00	2	2	38.07
1152	2.0	6.0	27	1.1	8	8.00	2	3	11.84
1153	1.0	4.0	11	.7	15	8.00	2	2	18.38
1154	3.0	3.0	14	1.5	2	3.00	2	2	15.01

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

Sample No.	V*	Cr*	Mn*	Fe%	Th*	U*	W*	Sr*	La*
gr0101	4	6	50	1.48	1.00	5.00	1	1.0	2.00
gr0102	48	59	259	14.05	1.00	5.00	1	10.0	4.00
GR0103	31	25	59	17.86	2.00	7.00	1	1.0	2.00
gr0104	78	18	538	3.33	1.00	5.00	1	17.0	5.00
gr0105	35	38	513	4.62	2.00	5.00	1	13.0	14.00
LS91130	16	7	230	41.87	2.00	5.00	1	3.0	2.00
LS91131	33	36	3326	23.64	3.00	5.00	1	41.0	15.00
LS91132	27	11	174	25.88	1.00	5.00	1	2.0	2.00
1150	4	1	5	24.83	3.00	6.00	1	1.0	2.00
1151	5	2	10	23.73	3.00	7.00	1	1.0	2.00
1152	97	49	729	21.35	4.00	11.00	1	19.0	14.00
1153	87	20	312	25.54	4.00	10.00	1	12.0	10.00
1154	22	21	1583	18.68	3.00	12.00	1	60.0	7.00

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

Sample No.	B*
gr0101	2
gr0102	7
GR0103	19
gr0104	2
gr0105	2
LS91130	3
LS91131	2
LS91132	8
1150	5
1151	5
1152	2
1153	3
1154	2

---

The fact sheet was created on 16.01.2025

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

Copyright © 2025 Geological Survey of Norway