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THE ???? DATABASE
Occurence 0 - 000 FEIL
(Object Id: )
(Last updated: 05.07.2023)
Location
County: Municipality: Mangler ()
Map 1:50000: Stjørdal (1621-1) Map 1:250000: Trondheim
County: UTM-Zone 33 - EUREF89/WGS84
Resource
Resource Type: Ferrous metals(Fe, Mn, Ti) Resource Subtype: Iron
Element(s): Fe
Importance
Raw material meaning: (No data)

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


Mineralization
Era: Paleozoic Period: Ordovician
Genesis: Volcex Form:
Main texture: Min. distribution: Massive (>50 % ore minerals)
Main grain size: Main alteration:
Strike/Dip: Direction:
Plunge:
Stratigraphic classification of host rock
Era: Paleozoic Period: Ordovician
Province: Caledonides
Geotec.unit: Trondheim Nappe Complex
Tectonic complex: Gula Complex
Igneous complex:
Group: Gula Formation:

Mineralogy
Relationship Mineral Amount
Gangue mineral Quartz Major mineral (>10%)
Gangue mineral Biotite Subordinate mineral (1-10%)
Ore mineral Magnetite Major mineral (>10%)

Lithology:
Relationship Rock Origin
Host rock Banded quartzite Sedimentary
Original rock :Exhalite
Metamorphic facies :Greenschist

Information(s) in free text format
Free text
Bjørnmyrgruva ligger i glissen granskog rett vest for ei myr i svært overdekket området ca. 150 m vest for gammelveien over Strandfjellet. Gruva ble drevet på ren magnetittmalm på 1820-tallet av Mostadmark jernverk. Den består av en vannfylt, tilnærmet trekantformet synk med lengste sider 4x6 m. Massiv magnetitt finnes i i fast fjell eller som en større blokk sørøst i synken. På tippen dominerer båndet kvartsittisk bergart i tillegg til finkornet, massiv magnetitt. Det er trolig at mineraliseringen er av samme type som ved Røsbekken som ligger 1,5 km lengre sør.

Bibliography:
From NGU's Reference Archive:
Torske, Tore , 1965
Geology of the Mostadmarka and Selbustrand area, Trøndelag.
;Norges geologiske undersøkelse;TIDSSKRIFTARTIKKEL;NGU; No.232;1-83 + ka pages
Abstract:
The bedrock of the area consists of metamorphic epiclastic, volcanic, and intrusive rocks of assumed Lower Ordovician age, assigned to, and lithologically matching the rocks of, the Røros, Støren and Lower Hovin Groups of the Trondheim Region. A detailed petrographic description of the rock varieties is given. The metamorphic grade of all rocks corresponds to the Greenschist Facies. - Small ore deposits occur in connection with the volcanic rocks. They comprise pyrite-pyrrhotite ores of the Leksdal Type, mixed pyrite-magnetite ores, and iron oxide ores. - Lithological variations of the sedimentary rocks is tentatively correlated with events during the early periods of the Caledonian Orogeny. - The volcanism within the area seems to have started with a phase of explosive activity, followed by extrusion (mostly submarine) of copious amounts of spilitic lavas; towards the end of the main period of volcanism a new episode of explosive activity has produced what is called the upper pyroclastic horizon, comprising rocks ranging from coarse volcanic breccia to finegrained tuffs. - The intrusive rocks consist mainly of saussurite gabbros and quartz keratophyres. The latter are thought to be intrusive rather than effusive, and evidence is offered to support this. In some places the character of pyroclastic material points to a quartz keratophyre parentage. Thus, quartz keratophyres may have occurred both as intrusive and volcanic rocks.

Fieldsamples
Sample No. Sample type Miscellanrous
Bjørnmyrgruva-1 Dump
Sampler: J.S.Sandstad/...Stored: Løkken/...Size(kg): 2
Comment: Massive, fine-grained magnetite med feldspar/apatite? Veinlets
No. of registrated element analyses = 1
No. of registrated oxide analyses = 1
NB! All analyse values are shown at the end of the printout.:

The fact sheet was created on 07.05.2024
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