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THE ORE DATABASE
Occurence 5022 - 026 Bergstjern I
(Object Id: 4533)
(Last updated: 01.07.1998)
Location
County: Trøndelag Municipality: Rennebu (5022)
Map 1:50000: Innset (1520-2) Map 1:250000: Røros
Coordinate system: EU89-UTM Zone 32
East: 556278 m. North: 6952068 m.
Longitude: 10.0996390 Latitude: 62.6948270
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Resource
Resource Type: Base metals (Cu,Zn,Pb,Fe sulphides, As,Sb,Bi,Sn) Resource Subtype: Sulphides
Element(s): Kis
Importance
Raw material meaning: Not Assessed (reg. 18.02.2015)

Resources and production
Activity: Test mining Reserves:
Operating method: Historical production:


Operations
From - To Activity Comments
1983 - 1984 Geochemistry Company/Institution :Folldal Verk A/S
1983 - 1985 Geophysics Company/Institution :Folldal Verk A/S
1984 - 1985 Sampling Company/Institution :Folldal Verk A/S
1984 - 1985 Geology Company/Institution :Folldal Verk A/S
1997 - 1997 Sampling Company/Institution :NGU-Malmreg.

Mineralization
Genesis: Volcex Form: Layer
Main texture: Banded Min. distribution: Semi-massive (20-50 % ore minerals)
Main grain size: Fine grained (< 1 mm) Main alteration:
Strike/Dip: 5 / 50 Direction:
Plunge:
Stratigraphic classification of host rock
Era: Period:
Province: Caledonides
Geotec.unit: Trondheim Nappe Complex
Tectonic complex: Støren Nappe
Igneous complex:
Group: Støren Formation:

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

Lithology:
Relationship Rock Origin
Host rock Quartz keratophyre Extrusive
Original rock :Tuff
Metamorphic facies :Greenschist
Wall rock Amphibole schist Sedimentary
Original rock :Tuffite
Metamorphic facies :Greenschist

Structures
Location: Type: Orientation(360 gr.): Relation to min.:
Host rock Foliation Strike/Dip :5 / 50 Post-mineralisation ;...Effect :None

Information(s) in free text format
Description
Folldal Verk A/S / Amoco utførte i 1983 regionale geofysiske helokoptermålinger i området, som i 1984-85 ble fulgt opp med detaljundersøkelser mellom Nyberget gruve og Bergstjern. Stikningsnett ble opprettet, fulgt av geologisk detaljkartlegging, geofysiske målinger (VLF, Mag, CEM), fastfjell- og jordprøvetaking. Bergstjern I ligger like vest for nordenden av Bergstjern. Mineraliseringen er undersøkt med ei 10 x 3 m2 stor strosse med synk. Hele skjerpet er vannfylt og vanskelig tilgjengelig. Mot kontakten til overliggende amfibolskifer er det i kvartskeratofyr tre opptil 10 cm mektige konkordante lag av massiv magnetkis-svovelkis-mineralisering over en mektighet på ca. 60 cm. Finkornig magnetkis er dominerende sulfid, men i enkelte bånd er det også endel svovelkis, da som 1 - 2 mm store korn. Mineraliseringens utstrekning er ukjent pga. overdekning.

Bibliography:
From NGU's Reference Archive:
Nilsen, Odd , 1978
Caledonian sulphide deposits and minor iron-formations from the southern Trondheim region, Norway.
;Norges geologiske undersøkelse;TIDSSKRIFTARTIKKEL;NGU; No.340;35-85 + k pages
Abstract:
Within the southern and central parts of the Trondheim region of the Norwegian Caledonides a great number of small, stratabound cupriferous pyrite deposits are confined to mafic metavolcanics of the Gula, Støren and Fundsjø Groups of the Lower Palaeozoic succession. The deposits occuring within, or in close contact with the metavolcanics are characterized by their association with minor manganiferous oxide/silicate iron-formations - better known as "vasskis" ore type - within the metamorphic low-grade areas. The iron-fprmations of the metamorphic higher grade terrains on the other hand, which are extensively developed within the Gula Group, are mostly of a pyrrhotitic sulphide/silicate type and sulphurization processes are thought to have played an important role during the metamorphism. The pyrite deposits occurring adjacent to the metavolcanics bear no relationship to the iron-formations. They are embedded in pelitic, often carbonaceous assemblages (Gula Group) or within tuffitic members of the volcanogene Støren Group, and they are thought to represent re-sedimented (reworked) deposits. The pyrite deposits display varying degree of metamorphic reconstitution and a tectonic control has apparently determined their disc- or ruler-shaped morphology.

References not to be found in NGU's Reference Archive.:
Bakke, O. 1984: Oppdal project. Intern rapp. Folldal Verk A/S. BV 3018


Bakke, O. 1984: Oppdal prosjekt. Intern rapp. Folldal Verk A/S. BV 3019

Fieldsamples
Sample No. Sample type Miscellanrous
ST0337.01 Dump
Sampler: Wilberg/...Stored: Løkken
Comment: Semimassiv po-min. i silifisert grønnskifer
No. of registrated element analyses = 1
NB! All analyse values are shown at the end of the printout.:

Analyse Results
from
Deposit Area 5022 - 026 Bergstjern I

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#
ST0337.01 Dump 228 271 5 -1 64 -.3 5.0
------------------
Sample No. Pt# Pd# As* Cd* Ba* Mo* Sb* Bi* S%
ST0337.01 -1.0 -1.0 47 .4 -1 6.00 5 -3 13.80
------------------
Sample No. V* Cr* Mn* Fe% Th* U* W* Sr* La*
ST0337.01 46 16 1994 26.03 6.00 -8.00 3 42.0 11.00
------------------
Sample No. B*
ST0337.01 -3

The fact sheet was created on 07.05.2024
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