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THE ORE DATABASE
Occurence 5025 - 042 Lomtjønna
(Object Id: 4374)
(Last updated: 27.10.2023)
Location
County: Trøndelag Municipality: Rosse (5025)
Map 1:50000: Røros (1720-3) Map 1:250000: Røros
Coordinate system: EU89-UTM Zone 32
East: 616229 m. North: 6938046 m.
Longitude: 11.2606350 Latitude: 62.5550100
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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: Little Importance (reg. 18.02.2015)

Resources and production
Activity: Mining Reserves:
Operating method: Open pit and underground mining Historical production:


Products
Element/product Crude ore grade or quality Reg. date
Cu 17.04.1998
Kis 17.04.1998

Operations
From - To Activity Comments
Test mining
1997 - 1997 Sampling Company/Institution :NGU

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

Mineralogy
Relationship Mineral Amount
Gangue mineral Chlorite Major mineral (>10%)
Gangue mineral Muscovite Major mineral (>10%)
Gangue mineral Quartz Subordinate mineral (1-10%)
Gangue mineral Garnet Subordinate mineral (1-10%)
Gangue mineral Amphibole Subordinate mineral (1-10%)
Ore mineral Pyrrhotite Major mineral (>10%)
Ore mineral Chalcopyrite Major mineral (>10%)
Ore mineral Pyrite Subordinate mineral (1-10%)
Ore mineral Magnetite Subordinate mineral (1-10%)

Lithology:
Relationship Rock Origin
Wall rock Semipelitic muscovite schist Sedimentary
Original rock :Greywacke
Metamorphic facies :Greenschist
Wall rock Metagabbro Intrusive
Original rock :Gabbro
Metamorphic facies :Greenschist

Structures
Location: Type: Orientation(360 gr.): Relation to min.:
Wall rock Foliation Strike/Dip :220 / 46
Wall rock Fold axis Dir./Plunge :258 / 21

Information(s) in free text format
Free text
Lomtjønna gruve ligger i tett skog i østvendt li ca. 600 m nordøst for Lomtjønna. Gruva består av en dagskjæring mot nordvest i en skrent ca. 5 m lang og 2-3 m dyp som fører inn til en vannfylt synk ca. 4 x 2.5 m i omriss. Forekomsten ligger på kontakten mellom semipelittisk muskovittskifer og en større kropp med metagabbro. Kontakten mellom bergartene er skarp. Mineraliseringen er tilknyttet skifrig og vesentlig biotitt-klorittomvandlet gabbro. Stedvis opptrer hyppig euhedral granat (2-3 mm) og 3-4 mm amfibolnåler. Mineraliseringen består hovedsaklig av mm til dm-tykke bånd med kobberkis og magnetkis, vesentlig i form av svake impregnasjoner, men også enkelte massive bånd. Ellers opptrer stedvis spredte < 1 mm pyrittkuber og < 1mm magnetitt-oktahedre.

Fieldsamples
Sample No. Sample type Miscellanrous
Lomtjønna-1 Dump
Sampler: T. Bjerkgård
No. of registrated element analyses = 1
ST0171.01 Dump
Sampler: Terje Bjerkgård/Leif Furuhaug/...Stored: Løkken/...Size(kg): 2
Comment: Semimassive bands (< 2 mm) of chalcopyrite and pyrrhotite in schistose amphibole-chlorite schist.
No. of registrated element analyses = 1
ST0171.02 Dump
Sampler: Terje Bjerkgård/Leif Furuhaug/...Stored: Løkken/...Size(kg): 2
Comment: Schistose metagabbro with very weak impregnation of pyrrhotite and chalcopyrite, occuring in mm-sized streaks.
No. of registrated element analyses = 1
ST0171.03 Dump
Sampler: Terje Bjerkgård/Leif Furuhaug/...Stored: Løkken/...Size(kg): 2
Comment: Amphibole-garnet-biotite-chlorite schist with weak impregnation as streaks of pyrrhotite, lesser chalcopyrite, scattered pyrite cubes and octahedrons of magnetite.
No. of registrated element analyses = 1
399706 Dump
Sampler: MINDEX ASA
No. of registrated element analyses = 1
NB! All analyse values are shown at the end of the printout.:

Name of Locality: Skjerp
(Object Id: 32704 42,01,00)
Location
County: Trøndelag Municipality: Rosse (5025)
Map 1:50000: Røros (1720-3) Map 1:250000: Røros
Coordinate system: EU89-UTM Zone 32
East: 616250 m. North: 6938100 m.
Longitude: 11.2610790 Latitude: 62.5554830
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Resource
Resource Type: Base metals (Cu,Zn,Pb,Fe sulphides, As,Sb,Bi,Sn) Resource Subtype: Sulphides
Element(s): Kis


Analyse Results
from
Deposit Area 5025 - 042 Lomtjønna

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#
Lomtjønna-1 Dump 61800 4830 9 280 68 13.2 426.0
ST0171.01 Dump 44732 4951 -3 311 82 9.5 446.0
ST0171.02 Dump 1146 164 3 59 19 -.3 1.0
ST0171.03 Dump 644 250 -3 46 40 -.3 2.0
399706 Dump 11000 919 23 97 37 1.2 283.0
------------------
Sample No. Pt# Pd# As* Cd* Ba* Mo* Sn* Sb* Bi*
Lomtjønna-1 2.5 .5 2 17.6 90 18.80 7 0 13
ST0171.01 2.0 -1.0 -2 21.8 38 10.00 -3 47
ST0171.02 -1.0 1.0 4 .6 -1 -1.00 4 -3
ST0171.03 3.0 2.0 3 1.1 203 -1.00 -3 3
399706 117 2.4 63 8.00 3 3
------------------
Sample No. Se* Ga* Ge* In* S% V* Cr* Mn* Fe%
Lomtjønna-1 116.00 11.05 0.49 5.47 10.00 81 46 2990 23.40
ST0171.01 13.00 70 56 904 22.69
ST0171.02 2.03 109 1 688 8.09
ST0171.03 .76 213 75 1256 12.53
399706 67 268 1272 12.10
------------------
Sample No. Th* U* W* Rb* Sr* Y* Zr* Nb* Ta*
Lomtjønna-1 3.19 1.00 0 22.7 38.9 10.4 15 3.10 0.25
ST0171.01 6.00 -8.00 -2 5.0
ST0171.02 -2.00 -8.00 -2 10.0
ST0171.03 3.00 -8.00 2 3.0
399706 8.0
------------------
Sample No. Cs* La* Ce* B* Li* Be* Sc* Ti* Te*
Lomtjønna-1 2.19 9.20 20.50 9 0 11.20 1547 12.95
ST0171.01 4.00 -3
ST0171.02 1.00 -3
ST0171.03 1.00 -3
399706 5.00 899
------------------
Sample No. Hf* Re* Tl*
Lomtjønna-1 0.40 0 1
ST0171.01
ST0171.02
ST0171.03
399706

The fact sheet was created on 25.10.2025
Questions or comments regarding the fact sheet can be emailed to:
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