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	THE ORE DATABASE
	Occurence 5026 - 007 Hessjø-Nygruva
	(Object Id: 10031) (Last updated: 19.03.2025)

Products

	Element/product	Crude ore grade or quality	Reg. date
	Cu		28.11.1997
	Kis		28.11.1997

Operations

	From - To	Activity	Comments
	1830 - 1830	Test mining	Company/Institution :Røros Kobberverk
			Drift på kobber
	1905 - 1905	Test mining	Company/Institution :Røros Kobberverk
			Pyritt
	1948 - 1948	Geophysics	Company/Institution :Geofysisk Malmleting
			Turam bakkemålinger
	1974 - 1974	Core drilling	Company/Institution :AS Sydvaranger
			3 hull over E-anomalien
	1974 - 1974	Geophysics	Company/Institution :NGU
			Helikoptermålinger, EM
	1975 - 1976	Geophysics	Company/Institution :NGU
			SP og VLF bakkemålinger

Mineralization

	Era:	Paleozoic	Period:	Ordovician
	Genesis:	Volcex	Form:	Plate
	Main texture:	Banded	Min. distribution:	Massive (>50 % ore minerals)

Main grain size:

Fine grained (< 1 mm)

Main alteration:

Chloritisation

	Strike/Dip:	200 / 60	Direction:
			Plunge:

Stratigraphic classification of host rock

Era:

Paleozoic

Period:

Ordovician

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

Group:

Fundsjø

Formation:

Mineralogy

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

Lithology:

	Relationship	Rock	Origin
	Wall rock	Greenstone	Extrusive Original rock :Basalt
			Metamorphic facies :Greenschist

Structures

	Location:	Type:	Orientation(360 gr.):	Relation to min.:
	Wall rock	Foliation	Strike/Dip :201 / 58	Post-mineralisation ;...Effect :Modifies
	Wall rock	Fold axis	Dir./Plunge :257 / 54	Post-mineralisation ;...Effect :Modifies

Information(s) in free text format

Free text

The Nygruva mine consists of an excavation in a small hillside, and two minor shafts. The excavation is 3-4 m across strike towards the west, before in turns to the north and follows a 1 meter thick zone of massive, fine-grained diffusely banded pyrite ore with subordinate sphalerite. The ore zone wedges out in both directions along strike, but may continue downwards along the strongly defined lineation/fold axis. In the footwall are numerous bands and lenses of disseminated to semimassive pyrite in quartz. One sample from the dump contained 1.71% Cu and 3.01% Zn. The closest shaft is about 70 m to the north. Here are two thin zones (20 and 80 cm wide) of massive, banded pyrite mineralization. Two samples contained 1.32 and 1.43% Cu and 0.99 and 7.94% Zn, respectively. The second shaft is another 70 m to the north. Here a sample of massive pyrrhotite ore with subordinate chalcopyrite and pyrite contained 1.76% Cu and 0.81% Zn. In all the samples from the Nygruva mine, the contents of Pb, Ag and Au were extremely low (highest values were 24 ppm Pb, 4 ppm Ag and 0.1 ppm Au). Three holes were drilled in 1974, guided by a weak EM anomaly associated with the outcropping mineralization. Hole no. 301 intersected 0.25 m with 3.00% Cu and 0.50% Zn, while holes no.302 and 303 intersected only weak pyrite impregnation.

Bibliography:

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

Se under Hesjø gruve (ST0188)

Fieldsamples

	Sample No.	Sample type	Miscellanrous
	ST0196.01	Dump	Sampler: Terje Bjerkgård/...Stored: Løkken/...Size(kg): 5 Comment: Banded, fine-grained, massive pyrite in quartz matrix. Frequent black spots of amphibole. No. of registrated element analyses = 1
	ST0196.02	Dump	Sampler: Terje Bjerkgård/...Stored: Løkken/...Size(kg): 5 Comment: Banded, fine-grained sphalerite with minor chalcopyrite in quartz matrix. No. of registrated element analyses = 1
	ST0196.03	Dump	Sampler: Terje Bjerkgård/...Stored: Løkken/...Size(kg): 5 Comment: Massive, fine-grained pyrite-sphalerite ore. No. of registrated element analyses = 1
	ST0196.04	Dump	Sampler: Terje Bjerkgård/...Stored: Løkken/...Size(kg): 5 Comment: Massive pyrrhotite-chalcopyrite with scattered mm-sized pyrite cubes. Non-sulfides include quartz and amphibole. No. of registrated element analyses = 1
	TB-Røros 23-02	Dump	Sampler: T. Bjerkgård/...Stored: Løkken Comment: Massive pyrite-sphalerite, banded, some chalcopyrite No. of registrated element analyses = 1
	TB-Røros 23-03	Dump	Sampler: T. Bjerkgård/...Stored: Løkken Comment: Semimassive pyrite with lenses of chalcopyrite No. of registrated element analyses = 1

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

Name of Locality: Pit

(Object Id: 32686 7,01,00)

Location

County:

Trøndelag

Municipality:

Holtålen (5026)

Map 1:50000:

Dalsbygda (1620-2)

Map 1:250000:

Røros

Coordinate system:

EU89-UTM Zone 32

East:

608865 m.

North:

6950751 m.

Longitude:

11.1256640

Latitude:

62.6712050

Show on map

Resource

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

Name of Locality: Pit

(Object Id: 32687 7,02,00)

Location

County:

Trøndelag

Municipality:

Holtålen (5026)

Map 1:50000:

Dalsbygda (1620-2)

Map 1:250000:

Røros

Coordinate system:

EU89-UTM Zone 32

East:

608900 m.

North:

6950814 m.

Longitude:

11.1263880

Latitude:

62.6717680

Show on map

Resource

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

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Analyse Results

from

Deposit Area 5026 - 007 Hessjø-Nygruva

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#
ST0196.01	Dump	13155	9861	10	150	7	1.9	15.0
ST0196.02	Dump	14294	79426	24	339	1	-.3	36.0
ST0196.03	Dump	17051	30145	20	161	9	4.2	102.0
ST0196.04	Dump	17572	8088	9	365	12	4.2	75.0
TB-Røros 23-02	Dump	14500	98900	27	728	5	6.8	100.0
TB-Røros 23-03	Dump	23800	1375	21	572	5	5.0	46.0

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

Sample No.	Pt#	Pd#	As*	Cd*	Ba*	Mo*	Sn*	Sb*	Bi*
ST0196.01	1.0	-1.0	23	18.1	2	1.00		3	4
ST0196.02	1.0	1.0	59	168.7	7	15.00		-3	-3
ST0196.03	-1.0	1.0	42	60.9	4	5.00		-3	6
ST0196.04	1.0	-1.0	40	22.4	6	-1.00		-3	6
TB-Røros 23-02	-5.0	5.0	187	210.0	-10	4.64	4	1	12
TB-Røros 23-03	-5.0	-1.0	83	3.8	-10	6.98	5	1	12

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

Sample No.	Se*	Ga*	Ge*	In*	S%	V*	Cr*	Mn*	Fe%
ST0196.01					42.86	2	-1	247	16.49
ST0196.02					41.91	6	-1	275	17.35
ST0196.03					34.29	6	-1	893	17.54
ST0196.04					37.81	12	6	336	21.97
TB-Røros 23-02	121.00	5.10	0.42	19.30	10.00	7	9	244	31.80
TB-Røros 23-03	83.00	0.35	0.32	4.88	10.00	2	9	47	33.40

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

Sample No.	Th*	U*	W*	Rb*	Sr*	Y*	Zr*	Nb*	Ta*
ST0196.01	-2.00	-8.00	2		1.0
ST0196.02	-2.00	-8.00	20		3.0
ST0196.03	-2.00	-8.00	-2		12.0
ST0196.04	-2.00	-8.00	-2		1.0
TB-Røros 23-02	0.02	0.10	0	0.1	0.8	1.4	-1	-0.10	-0.05
TB-Røros 23-03	0.01	0.20	0	-0.1	-0.2	1.0	-1	-0.10	-0.05

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

Sample No.	Cs*	La*	Ce*	B*	Li*	Be*	Na*	Mg*	Al*
ST0196.01		-1.00		-3
ST0196.02		-1.00		-3
ST0196.03		1.00		-3
ST0196.04		-1.00		3
TB-Røros 23-02	-0.05	-0.50	0.39		-0	-0	100	1700	2500
TB-Røros 23-03	-0.05	-0.50	0.38		-0	-0	100	300	400

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

Sample No.	P*	K *	Ca*	Sc*	Ti*	Te*	Hf*	Re*	Tl*
ST0196.01
ST0196.02
ST0196.03
ST0196.04
TB-Røros 23-02	20	-100	700	1.00	80	10.75	-0.10	-0	1
TB-Røros 23-03	10	-100	100	0.10	-50	9.78	-0.10	0	0

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The fact sheet was created on 12.07.2025

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

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