Norsk versjon
THE ORE DATABASE
Occurence 5043 - 003 Stortjern
(Object Id: 229)
(Last updated: 16.05.2006)
Location
County: Trøndelag Municipality: Raarvihke (5043)
Map 1:50000: Skorovatn (1824-2) Map 1:250000: Grong
Coordinate system: EU89-UTM Zone 33
East: 409472 m. North: 7179099 m.
Longitude: 13.0996080 Latitude: 64.7244120
Show on map
Resource
Resource Type: Base metals (Cu,Zn,Pb,Fe sulphides, As,Sb,Bi,Sn) Resource Subtype: Sulphides
Element(s): Kis
Importance
Raw material meaning: Little Importance (reg. 18.02.2015)

Resources and production
Activity: Exploration Reserves:
Operating method: Historical production:


Operations
From - To Activity Comments
1973 - 1980 Geology Company/Institution :Grong Gruber A/S
1974 - 1974 Geophysics Company/Institution :Grong Gruber A/S
1981 - 1981 Geophysics Company/Institution :Grong Gruber A/S
1994 - 1996 Geology Company/Institution :NGU

Mineralization
Era: Paleozoic Period: Ordovician
Genesis: Volcex Form: Irregular
Main texture: Structureless Min. distribution: Disseminated (<20 % ore minerals)
Main grain size: Fine grained (< 1 mm) Main alteration: Pyritisation
Strike/Dip: Direction:
Plunge:
Stratigraphic classification of host rock
Era: Paleozoic Period: Ordovician
Province: Caledonides
Geotec.unit: Køli Nappe Complex
Tectonic complex: Gjersvik Nappe
Igneous complex:
Group: Gjersvik Formation:

Mineralogy
Relationship Mineral Amount
Gangue mineral Chlorite Major mineral (>10%)
Gangue mineral Quartz Major mineral (>10%)
Gangue mineral Plagioclase Major mineral (>10%)
Ore mineral Pyrite Major mineral (>10%)

Lithology:
Relationship Rock Origin
Host rock Quartz keratophyre Extrusive
Original rock :Rhyodacite
Metamorphic facies :Greenschist
Host rock Greenstone Extrusive
Original rock :Basalt
Metamorphic facies :Greenschist

Structures
Location: Type: Orientation(360 gr.): Relation to min.:
Host rock Foliation Strike/Dip :222 / 30 Post-mineralisation ;...Effect :Modifies

Information(s) in free text format
Free text
Det er ikke registrert skjerp i området som ligger 3-5 km nord for Tunnsjøflyin. Koordinatene til hovedforekomsten er angitt til en av de større og mere utholdende rustsonene i området. Flere parallelle rustsoner over en bredde på 15-20 m finnes og kan følges 150-200 m. Grong Gruber A/S fattet interesse for området fordi Turam-målingene med utgangspunkt i Småvatn i 1974 ga mange, spredte anomalier. VLF-målinger og befaringer har vist at området har flekkvise konsentrasjoner av svovelkis disseminasjon i en fint skifrig og småfoldet grønnstein. Den er laminert med tynne keratofyrbånd og mektigere keratofyrer med svovelkis disseminasjon finnes også. Mektigheten på de enkelte sulfidsonene kan være opptil 3-4 m. Analyser viser lave gehalter av basemetaller, eks. opptil 0,09 % Zn. I tillegg til pyrittisering er klorittisering og silisifisering de mest vanlige omvandlingstypene.

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).

Fieldsamples
Sample No. Sample type Miscellanrous
JS96069 Bedrock
Sampler: Sandstad, J.S./...Stored: Løkken
Comment: Pyrite dissemination, weak to moderate, in chloritized greenstone.
No. of registrated element analyses = 1
NB! All analyse values are shown at the end of the printout.:

Name of Sample point: Prøvepkt. 1
(Object Id: 8987 3,00,01)
Location
County: Trøndelag Municipality: Raarvihke (5043)
Map 1:50000: Skorovatn (1824-2) Map 1:250000: Grong
Coordinate system: EU89-UTM Zone 33
East: 408862 m. North: 7179079 m.
Longitude: 13.0868240 Latitude: 64.7240670
Show on map
Resource
Resource Type: Base metals (Cu,Zn,Pb,Fe sulphides, As,Sb,Bi,Sn) Resource Subtype: Sulphides
Element(s): Kis


Fieldsamples
Sample No. Sample type Miscellanrous
JS96071 Bedrock
Sampler: Sandstad, J.S./...Stored: Løkken
Comment: Pyrite dissemination/veinlets in silicified quartz keratophyre.
No. of registrated element analyses = 1
JS96072 Bedrock
Sampler: Sandstad, J.S./...Stored: Løkken
Comment: Pyrite dissemination/veinlets in silicified and chloritised amphibolite.
No. of registrated element analyses = 1
NB! All analyse values are shown at the end of the printout.:

Name of Sample point: Prøvepkt. 2
(Object Id: 8988 3,00,02)
Location
County: Trøndelag Municipality: Raarvihke (5043)
Map 1:50000: Skorovatn (1824-2) Map 1:250000: Grong
Coordinate system: EU89-UTM Zone 33
East: 409782 m. North: 7180179 m.
Longitude: 13.1054340 Latitude: 64.7341800
Show on map
Resource
Resource Type: Base metals (Cu,Zn,Pb,Fe sulphides, As,Sb,Bi,Sn) Resource Subtype: Sulphides
Element(s): Kis


Fieldsamples
Sample No. Sample type Miscellanrous
JS96066 Bedrock
Sampler: Sandstad, J.S./...Stored: Løkken
Comment: Pyrite dissemination, moderate-strong, in quartz rich, silicified keratophyre.
No. of registrated element analyses = 1
NB! All analyse values are shown at the end of the printout.:

Name of Sample point: Prøvepkt. 3
(Object Id: 8989 3,00,03)
Location
County: Trøndelag Municipality: Raarvihke (5043)
Map 1:50000: Skorovatn (1824-2) Map 1:250000: Grong
Coordinate system: EU89-UTM Zone 33
East: 410052 m. North: 7179969 m.
Longitude: 13.1112320 Latitude: 64.7323690
Show on map
Resource
Resource Type: Base metals (Cu,Zn,Pb,Fe sulphides, As,Sb,Bi,Sn) Resource Subtype: Sulphides
Element(s): Kis


Fieldsamples
Sample No. Sample type Miscellanrous
JS96065 Bedrock
Sampler: Sandstad, J.S./...Stored: Løkken
Comment: Pyrite-quartz veinlets and pyrite disseminations in chlorite-rich greenstone.
No. of registrated element analyses = 1
NB! All analyse values are shown at the end of the printout.:

Analyse Results
from
Deposit Area 5043 - 003 Stortjern

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#
JS96065 Bedrock 210 572 15 25 136 .8 10.0
JS96066 Bedrock 103 20 4 4 12 .5 16.0
JS96069 Bedrock 120 764 -3 25 174 -.3 10.0
JS96071 Bedrock 5 42 3 5 2 -.3 3.0
JS96072 Bedrock 112 178 30 82 22 -.3 8.0
------------------
Sample No. Pt# Pd# Rh# As* Cd* Ba* Mo* Sb* Bi*
JS96065 -1.0 -1.0 -1.0 6 .3 26 -1.00 -2 2
JS96066 -1.0 -1.0 -1.0 4 -.2 2 4.00 -2 4
JS96069 2.0 4.0 -1.0 -2 3.0 11 2.00 -2 -2
JS96071 -1.0 -1.0 -1.0 -2 -.2 10 2.00 -2 2
JS96072 -1.0 -1.0 -1.0 51 .5 16 -1.00 -2 -2
------------------
Sample No. S% V* Cr* Mn* Fe% Th* U* W* Sr*
JS96065 1.19 217 364 3166 10.67 -2.00 7.00 -2 6.0
JS96066 4.39 11 3 64 6.78 -2.00 -5.00 -2 1.0
JS96069 1.19 230 479 3687 15.64 -2.00 11.00 -2 4.0
JS96071 1.26 15 3 368 3.01 -2.00 -5.00 -2 27.0
JS96072 2.89 77 44 1707 9.41 -2.00 6.00 -2 8.0
------------------
Sample No. La* B*
JS96065 1.00 9
JS96066 -1.00 -3
JS96069 1.00 3
JS96071 7.00 -3
JS96072 2.00 -3

The fact sheet was created on 07.05.2024
Questions or comments regarding the fact sheet can be emailed to:
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