(Last updated: 22.03.2024)
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Norsk versjon | ||||
| THE ORE DATABASE | |||||
| Prospect 1813 - 025 Målvika | |||||
| (Object Id: 2191) (Last updated: 22.03.2024) |
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| Location |
| County: | Nordland | Municipality: | Brønnøy (1813) |
| Map 1:50000: | Tosbotn (1825-1) | Map 1:250000: | Mosjøen |
| Coordinate system: | EU89-UTM Zone 33 |
| East: | 400520 m. | North: | 7243799 m. |
| Longitude: | 12.8659930 | Latitude: | 65.3020360 |
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| Resource |
| Resource Type: | Ferroalloys (Cr,Ni,Co,V,Mo,W) | Resource Subtype: | Wolfram | |
| Element(s): | W |
| Importance |
| Raw material meaning: | Not Assessed (reg. 07.12.2015) |
| Resources and production |
| Activity: | Exploration | Reserves: | 750 thousand tons | |
| Operating method: | Historical production: |
Products |
| Element/product | Crude ore grade or quality | Reg. date | |
| W | 0.35 % | 17.10.2017 |
Mineralization |
| Genesis: | Form: | |||
| Main texture: | Min. distribution: |
| Main grain size: | Main alteration: |
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| Stratigraphic classification of host rock |
| Era: | Period: |
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Information(s) in free text format |
| Free text |
| The Målvika wolfram deposit comprises scheelite mineralisation which occasionally yield analytical values of 1-2 ppm Au together with enhanced contents of As and Bi. Scheelite as dissemination and veinlets occurs together with coprecipitated epidote and amphibole in plagioclase-clinopyroxene and garnet skarns. The skarns replace hornblende-biotite gneisses with units of calcitic marbles. The up to 60 m wide and 900 m long heterogeneous skarn zone with highly variable contents of scheelite are intersected by numerous granite dykes locally containing fractures coated by auriferous arsenopyrite. |
Bibliography: |
| From NGU's Reference Archive: |
| Müller, Axel ; Furuhaug, Leif , 2008 |
| Resource evaluation of the Målvika tungsten deposit, Nordland |
| ;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.2008.008;49 s. + 1 pages |
| Abstract: | |
| Nordic Mining contacted NGU in spring 2007 in order to re-evaluate the resource and grade of the Målvika tungsten deposit in Tosbotn municipality in Nordland, Norway. The Målvika tungsten deposit is a tungsten skarn mineralisation which extends 900 m NNW-ward from the northern coastline of Tosenfjord towards mountain Landnubben and ends at an altitude of about 500 m a.s.l. The skarn zone comprises marbles, metasomatic calc-silicate rocks (skarn sensu strictu), skarn-altered gneisses and granites. The ore-bearing diopside and garnet-diopside skarns form individual boudins (lenses) usually smaller than 5 m in length and 2 m in width, aligned in vein-like structures commonly 2 m wide and up to two hundred metres long. Scheelite ore is accumulated in 1-20 cm large batches distributed very heterogeneously within complexly folded and boudinaged skarns. The deposit has previously been the target of three exploration phases with contrasting results since its discovery in 1972 by P. Skaarup. Some results indicate that the Målvika skarn in a world-class tungsten resource having an ore tonnage of 2 509 000 t with a grade 0.7 to 0.9 wt.% WO3, while a drilling project performed in 1983 by Sulfidmalm AS indicated only traces of tungsten. Fieldwork was carried out during two campaigns in July and October 2007. The first campaign included 393 in situ analyses of the tungsten concentration of different rock types in the mineralised zone using a portable X-ray fluorescence diffraction spectrometer. During the second campaign, 66 bulk rock trench samples were taken, transecting nine different skarn layers. The results indicate that the Målvika skarn zone is a minor tungsten deposit with possible mineable ore tonnage of 750 000 t diopside and garnet-diopside skarn with an ore grade of about 0.44 wt.% WO3. The granites of the Visttindane massif sampled 0.5 to 1 km E of Målvika have a high average tungsten content of 121 ppm reflecting an extreme enrichment of tungsten in the granite magmas. Thus, these granites are the most likely source of the tungsten and the Målvika deposit is an intrusion-related skarn. The mineralisation was presumably formed 430-440 Ma years ago. This result suggests that there is the possibility of finding more tungsten deposits within a radius of 5 km around the Visttindane granite massife, or within the pluton. |
| James, D. Wyn; Mitchell, John G.; Ineson, Richard; Nordgulen, Øystein , 1993 |
| Geology and K/Ar chronology of the Målvika scheelite skarns, Central Norwegian Caledonides. |
| ;Norges geologiske undersøkelse;TIDSSKRIFTARTIKKEL;NGU Bulletin; No.424;65-74 pages |
| Abstract: | |
| Skarns present on the northern shore of Tosenfjord overprint the S2 fabric of the adjacent gneiss (which formed during peak regional metamorphism). Together with petrographic evidence of the late crystallization of sheelite, this indicates that mineralization was post-metamorphic and epigenetic. K/Ar apparent ages of mine mineral separates (four post-scheelite amphiboles from skarn, two muscovites and three biotites from intrusions) are concordant at the 1q level, giving an inverse Variance Weighted Mean (VWM) age of 402 +- 2 Ma The close agreement of results from different minerals points to rapid post-orogenic uplift in the Central Scandinavian Caledonides. Two other post-scheelite amphibole skarn samples gave indistinguishable (at 1q) apparent ages whose mean is 472 Ma. If valid, this age would substantially constrain the timing of regional metamorphism and mineralization. However, the possibility that the age are spurious, due to the presence of excess argon, cannot be excluded, |
Fieldsamples |
| Sample No. | Sample type | Miscellanrous | |||
| NO0065.01 | Bedrock |
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| NO0065.02 | Bedrock |
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| NO0065.03 | Bedrock |
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| NO0065.04 | Bedrock |
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| NO0065.05 | Bedrock |
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| NO0065.06 | Bedrock |
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| NO0065.07 | Bedrock |
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| NO0065.08 | Bedrock |
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| NO0065.09 | Bedrock |
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| NO0065.10 | Bedrock |
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| NO0065.11 | Bedrock |
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| NO0065.12 | Bedrock |
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| NO0065.13 | Bedrock |
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| NO0065.14 | Bedrock |
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| NO0065.15 | Bedrock |
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| NO0065.16 | Bedrock |
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| NO0065.17 | Bedrock |
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| NO0065.18 | Bedrock |
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| NO0065.19 | Bedrock |
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| NO0065.20 | Bedrock |
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| NO0065.21 | Bedrock |
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| NO0065.22 | Bedrock |
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| NO0065.23 | Bedrock |
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| NO0065.24 | Bedrock |
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| NO0065.25 | Bedrock |
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| NO0065.26 | Bedrock |
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| NO0065.27 | Bedrock |
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| NO0065.28 | Bedrock |
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| NO0065.29 | Bedrock |
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| NO0065.30 | Bedrock |
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| NO0065.31 | Bedrock |
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| NO0065.32 | Bedrock |
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| NO0065.33 | Bedrock |
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| NO0065.34 | Bedrock |
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| NO0065.35 | Bedrock |
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| NO0065.36 | Bedrock |
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| NO0065.37 | Bedrock |
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| NO0065.38 | Bedrock |
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| NO0065.39 | Bedrock |
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| NO0065.40 | Bedrock |
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| NO0065.41 | Bedrock |
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| NO0065.42 | Bedrock |
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| NO0065.43 | Bedrock |
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| The fact sheet was created on 26.04.2024 |
| Questions or comments regarding the fact sheet can be emailed to: ressursdatabaser@ngu.no |
| Copyright © 2024 Geological Survey of Norway |