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THE ORE DATABASE
Prospect 3047 - 022 Skuterud Nordgruver
(Object Id: 5903)
(Last updated: 16.03.2020)
Belongs to the Province: Modum Vest

Location
County: Viken Municipality: Modum (3047)
Map 1:50000: Hokksund (1714-1) Map 1:250000: Skien
Coordinate system: EU89-UTM Zone 32
East: 548211 m. North: 6649252 m.
Longitude: 9.8637970 Latitude: 59.9777870
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Resource
Resource Type: Ferroalloys (Cr,Ni,Co,V,Mo,W) Resource Subtype: Cobalt
Element(s): Co Cu As
Importance
Raw material meaning: Not Assessed (reg. 09.02.2017)

Resources and production
Activity: Mining Reserves:
Operating method: Open pit and underground mining Historical production: 140 thousand tons


Products
Element/product Crude ore grade or quality Reg. date
Co 0.2 % 31.08.2010

Mineralization
Genesis: Form:
Main texture: Min. distribution:
Main grain size: Main alteration:
Strike/Dip: Direction:
Plunge:
Stratigraphic classification of host rock
Era: Period:
Province:
Geotec.unit:
Tectonic complex:
Igneous complex:
Group: Formation:

Information(s) in free text format
Free text
The cobalt ores at Skuterud were found in 1772, and ordinary production started in 1776. First in large open pits, but from 1827 until the closure in 1898, mining was done underground. In the 1890s, ore reserves decreased rapidly, leading to the final shutdown of mining operation in 1898. On the basis of different old mining reports the total production is estimated to 1 Mt with 0.2 % Co. In addition to cobalt, the ores contain significant grades of copper (up to 1-2 %) and locally enrichment of gold (several ppm). The cobalt occurrences at Modum are related to sulphide-rich schist zones, so-called fahlbands. The most extensive sulphide-rich zone has a length of 12 km along strike, and is up to 100–200 m wide. The rock type hosting the sulphides may be characterized as a quartz-plagioclase-tourmaline-phlogopite-sulphide gneiss or schist. Graphite is locally common and its content may attain more than 5 % of the rock. The cobalt mineralisation is, to a large degree, characterised by impregnation of cobaltite (CoAsS), glaucodote ((Co,Fe)AsS), safflorite ((Co,Fe)As2) and skutterudite (CoAs3), which partly occur as enriched in quartz-rich zones and lenses. The cobalt-rich lenses are structurally controlled, following axes of folds and lineations in the area.

Photo(s) from the Deposit area:
Photo no. 1 showing Nordgruvene"
Photo no. 2 showing Erythrin"

Bibliography:
From NGU's Reference Archive:
Grorud, Hans-Fredrik , 1997
Textural and compositional characteristics of cobalt ores from the Skuterud Mines of Modum, Norway
;Norsk geologisk forening;TIDSSKRIFTARTIKKEL;Norsk geologisk tidsskrift; No.77 (1);31-38 pages
Abstract:
The metasedimentary rocks of the Modum Complex contain concordant, sulphide- rich zones, commonly referred to as 'fahlbands'. Two of these fahlbands contain cobalt minerals. Petrographic and microprobe analyses of the cobalt minerals have been performed on selected samples, to gain insight into the genesis and post-mineralization history of the cobalt minerals. It is suggested that these minerals precipitated from an oxidizing fluid, and that certain minerals in the uraninite.thorianite series precipitated simulataneously. The fahlband silicates, and later the cobalt minerals, were recrystallized during Sveco- norwegian penetrative deformation and thermal maximum (-1.2- -0.9Ga). Prolonged heating during this event eradicated any compositional zoning which may originally have been present. Neither textural nor mineral chemical analyses indicate whether the observed cobalt minerals are the result of a primary precipitation, or of remobilization.

Name of Locality: Gruve 6
(Object Id: 32742 22,01,00)

Location
County: Viken Municipality: Modum (3047)
Map 1:50000: Hokksund (1714-1) Map 1:250000: Skien
Coordinate system: EU89-UTM Zone 32
East: 548292 m. North: 6649459 m.
Longitude: 9.8652970 Latitude: 59.9796440
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Resource
Resource Type: Ferroalloys (Cr,Ni,Co,V,Mo,W) Resource Subtype: Cobalt
Element(s): Co As


The fact sheet was created on 18.10.2021

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