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THE ORE DATABASE
Occurence 1114 - 005 Hovland
(Object Id: 4889)
(Last updated: 18.07.2023)
Location
County: Rogaland Municipality: Bjerkreim (1114)
Map 1:50000: Ørsdalsvatnet (1312-3) Map 1:250000: Mandal
Coordinate system: EU89-UTM Zone 32
East: 351177 m. North: 6506519 m.
Longitude: 6.4335160 Latitude: 58.6732760
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Resource
Resource Type: Ferroalloys (Cr,Ni,Co,V,Mo,W) Resource Subtype: Molybdenium
Element(s): Mo W
Importance
Raw material meaning: Not Assessed (reg. 18.02.2015)

Resources and production
Activity: Test mining Reserves:
Operating method: Underground mining Historical production: 1,8 thousand tons


Mineralization
Era: Proterozoic Period: Neoproterozoic
Genesis: Hydrothermal vein Form: Irregular
Main texture: Structureless Min. distribution: Disseminated (<20 % ore minerals)
Main grain size: Very unevenly grained Main alteration:
Strike/Dip: 305 / 80 Direction:
Plunge:
Stratigraphic classification of host rock
Era: Proterozoic Period: Mesoproterozoic
Province: South Norwegian Basement Province
Geotec.unit: Agder Complex
Tectonic complex: Sirdal Magmatic Belt
Igneous complex:
Group: Formation:

Mineralogy
Relationship Mineral Amount
Gangue mineral Feldspar Major mineral (>10%)
Gangue mineral Quartz Major mineral (>10%)
Gangue mineral Biotite Subordinate mineral (1-10%)
Ore mineral Molybdenite Major mineral (>10%)
Ore mineral Scheelite Subordinate mineral (1-10%)
Ore mineral Wolframite Subordinate mineral (1-10%)

Lithology:
Relationship Rock Origin
Host rock Biotite-hornblende gneiss Intrusive
Metamorphic facies :Amphibolite
Host rock Granite Intrusive
Original rock :Granite
Metamorphic facies :Amphibolite

Structures
Location: Type: Orientation(360 gr.): Relation to min.:
Host rock Mineral banding Strike/Dip :305 / 80 Pre-mineralisation ;...Effect :None

Information(s) in free text format
Free text
Hovland gruve er anlagt som en grunnstoll til W-Mo mineraliseringene i Sandnesskjerpene. De ligger langs den vestligste av de to subparallelle, NV-SØ orienterte mineraliserte sonene i Ørsdalen. Denne sonen er ca. 300 m lang og domineres av rikere mineralisering av molybden enn wolfram. Mo-mineraliseringene finnes som regel i granittt. Stollen har retning 55 grader og er drevet inn fra østsida av Grubetjørna. Den er vannfylt og ved inngangen dominerer porfyrisk granitt. Molybdenglans finnes langs stikk og som aggregater i granitt på tippen som utgjør ca. 600 kbm.

Bibliography:
From NGU's Reference Archive:
Heier, K. , 1954
En geologisk undersøkelse av bergartene og malmforekomstene i Ørsdalen.
;Norges geologiske undersøkelse;FAGRAPPORT;Bergarkivet; No.BA 3938;135 pages
Abstract:
Rapporten er et hovedfagsarbeide og gir en bred utredning om Ørsdalsfeltets geologi. Følgende tema blir spesielt behandlet: - Petrografi. - Granitisering. - Malmgeologi. - Metamorfose. - Tektonikk. I rapportteksten er det en rekke fotografier, diagrammer, figurer og analyser.

Heier, Knut , 1956
The geology of the Ørsdalen district, Rogaland, S. Norway.
;Norsk geologisk forening;TIDSSKRIFTARTIKKEL;Norsk geologisk tidsskrift; No.36 (3/4);167-211 pages
Abstract:
The tungsten and molybdenite deposit in the area has been dealt with earlier by the author; this paper deals with the general geology, petrology and rock metamorphism of the region. After the regional geology has been briefly described, the paper deals with the petrographical classification of the rocks exposed. These are amphibolites and two types of quartzo-feldspathic gneisses. Then follows a short description of the rock structures. It is shown how a heavy folding of orogenic nature has effected all the rocks and it is concluded that they must have reacted to the folding in a plastic way. A chapter where the metasomatic processes are discussed follows next and the conclusions reached are that the one kind of the gneisses may have originated through metasomatism of anorthositic rocks while strong evidence is that the other has been formed by replacement of amphibolites and related rocks. The metasomatism is belived to be synkinematic. The metamorphism is dealt with at some length and it is shown that all the rocks must once have belonged to granulite facies, which is also the PT conditions during which the metasomatism took place. Later a retrograde metamorphism has affected the rocks within certain zones which are believed to represent tectonical zones of weakness. A map showing the metamorphic situation of the area is presented and here a division of the rocks into three groups according to differences in metamorphism is undertaken. These are: high amphibolite facies (including granulite facies), low amphibolite facies, epidote amphibolite- and greenschist facies. It is shown how a division of the rocks into one of these three groups can be based upon variations in the minerals of the quartzo-feldspathic gneisses alone. The paper ends with some considerations upon the relative age of the Telemark and Egersund formations of pre-Cambrian rocks. Based on the

Heier, Knut , 1955
The Ørsdalen tungsten deposit.
;Norsk geologisk forening;TIDSSKRIFTARTIKKEL;Norsk geologisk tidsskrift; No.35 (1-4);69-85 pages
Abstract:
The general geology and the type of mineralization are shortly discussed, and the different ore minerals occurring are described. The minerals show a zoning opposite to what is generally considered the rule. Special attention is directed to the tungsten minerals (wolframite and scheelite) and it is shown how wolframite is altered into scheelite. This process is ascribed to a Ca metasomatism, probably brought about by late hydrothermal solutions reacting with the already formed wolframites. Experimental work has proved this reaction to go rather quickly. In the field this process is connected in time with other processes traceable in the history of the rocks. The formation of the ore is very briefly discussed.

Olerud, Svein , 1980
Geologiske og geokjemiske undersøkelser rundt Ørsdalen W-Mo forekomst.
;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.1750/51A;34 pages
Abstract:
Rapporten tar for seg de geologiske og geokjemiske forhold i området rundt Ørsdalen W-Mo forekomst og behandler resultatene av geokjemiske undersøkelser i et 50 kv. kilom. stort område rundt forekomsten. W-Mo i forekomsten er knyttet til bånd i en antiform struktur, men mineraliseringen er uregelmessig og vanskelig å følge. De kjente forekomster er rike nok til å være økonomisk interessante men reservene er for små. Mellom Schånnings gruve og stoll1 er et 400 m høyt parti som ikke er undrsøkt. Videre boring her vil bli vanskelig og kostbar p.g.a utilgjengelig terreng. Geokjemien i området gir utslag for de kjente forekomster pluss noen anomalier utenom. Oppfølgingen av anomaliene ga negativt resultat. W i bekkesedimenter viste seg å være et bra alternativ til tungmineralvasking.

References not to be found in NGU's Reference Archive.:
Sandberg, P.C. 1953. Oversikt over utfølrte arbeider og foreløpige undersøelser. BV rapprt 7135, 5s.


Bjørlykke, H. 1953. Ørsdalen Wolframforekomst. BV Rapport 1142, 9s.


Bjørlykke, H. 1952. Bergverksrapporter Mjåvassknuden, Ørsdalen. BV Rapport 7163, 6s.


Limyr, O. 1983. Eksploration works 1982. Fallverk A7S Norske Fina A/S. BV Rapport 1134, 18s.

Fieldsamples
Sample No. Sample type Miscellanrous
JS-W2106 Dump
Sampler: J.S.Sandstad/...Stored: Løkken/...Size(kg): 2
Comment: Molybdenite veinlets/aggregates in granite in contact with amphibolite
No. of registrated element analyses = 1
NB! All analyse values are shown at the end of the printout.:

Name of Locality: Sandnesskjerpene synk
(Object Id: 38448 5,01,00)
Location
County: Rogaland Municipality: Bjerkreim (1114)
Map 1:50000: Ørsdalsvatnet (1312-3) Map 1:250000: Mandal
County: (Unavailable)
Resource
Resource Type: Ferroalloys (Cr,Ni,Co,V,Mo,W) Resource Subtype: Molybdenium
Element(s): Mo W
Resources and production
Activity: Test mining Reserves:
Operating method: Underground mining Historical production:


Information(s) in free text format
Free text
Sandnessynken ligger ca. 50 m NV for og ca. 35 m høyere i terrenget enn stollinngangen til Hovland gruve. Den er en liten vannfylt og har sidevegger på 3 x 1,5 m. Den er drevet langs kontakten mellom grovkornet granitt i nordøst og migmatittisk biotitt-gneis i sørvest. Relativt rik molybdenglans-mineralisering finnes som aggregater, disseminert og på stikk i granitten.

Fieldsamples
Sample No. Sample type Miscellanrous
JS-W2105 Dump
Sampler: J.S.Sandstad/...Stored: Løkken/...Size(kg): 2
Comment: Molybdenite dissemination/aggregates in granite
No. of registrated element analyses = 1
NB! All analyse values are shown at the end of the printout.:

Name of Locality: Sandnesskjerpene SØ
(Object Id: 38449 5,02,00)
Location
County: Rogaland Municipality: Bjerkreim (1114)
Map 1:50000: Ørsdalsvatnet (1312-3) Map 1:250000: Mandal
Coordinate system: EU89-UTM Zone 32
East: 351259 m. North: 6506523 m.
Longitude: 6.4349260 Latitude: 58.6733400
Show on map
Resource
Resource Type: Ferroalloys (Cr,Ni,Co,V,Mo,W) Resource Subtype: Molybdenium
Element(s): Mo W
Resources and production
Activity: Test mining Reserves:
Operating method: Open pit mining Historical production:


Information(s) in free text format
Free text
Dette er en ca. 18 m, 3-4 m bred og opptil 3 m høy dagskjæring som ligger ca. 50 m sørøst for Sandnessynken. Middel- til grovkornet granitt dominerer i skjerpet. Molybdenglans opptrer disseminert, i aggregater og i kvartsårer/linser i granitt. En prøve av denne inneholder 4,5 % Mo.

Fieldsamples
Sample No. Sample type Miscellanrous
JS-W2107 Dump
Sampler: J.S.Sandstad/...Stored: Løkken/...Size(kg): 2
Comment: Molybdenite, strong dissemination/aggregates in granite
No. of registrated element analyses = 1
NB! All analyse values are shown at the end of the printout.:

Name of Locality: Sandnesskjerpene NV
(Object Id: 38450 5,03,00)
Location
County: Rogaland Municipality: Bjerkreim (1114)
Map 1:50000: Ørsdalsvatnet (1312-3) Map 1:250000: Mandal
Coordinate system: EU89-UTM Zone 32
East: 351095 m. North: 6506650 m.
Longitude: 6.4320170 Latitude: 58.6744230
Show on map
Resource
Resource Type: Ferroalloys (Cr,Ni,Co,V,Mo,W) Resource Subtype: Molybdenium
Element(s): Mo W
Resources and production
Activity: Pitting Reserves:
Operating method: Historical production:


Information(s) in free text format
Free text
Dette er et mindre skjerp ca. 150 m NV for Sandnessynken.

Analyse Results
from
Deposit Area 1114 - 005 Hovland

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#
JS-W2105 Dump 503 115 12 11 18 1.1 4.0
JS-W2106 Dump 129 341 23 33 51 .5 1.0
JS-W2107 Dump 62 180 15 8 7 .3 -1.0
------------------
Sample No. Pt# Pd# As* Cd* Ba* Mo* Sn* Sb* Bi*
JS-W2105 -5.0 3.0 0 .8 340 13900.00 2 0 1
JS-W2106 -5.0 1.0 0 1.0 520 9170.00 7 0 1
JS-W2107 -5.0 1.0 1 1.4 400 45400.00 5 0 0
------------------
Sample No. Se* Ga* Ge* In* S% V* Cr* Mn* Fe%
JS-W2105 3.00 10.80 0.08 0.09 1.95 41 17 478 4.32
JS-W2106 3.00 32.20 0.21 0.21 1.06 224 79 1635 10.50
JS-W2107 17.00 20.90 0.21 0.18 3.21 81 13 868 5.85
------------------
Sample No. Th* U* W* Rb* Sr* Y* Zr* Nb* Ta*
JS-W2105 0.47 0.60 75 94.5 38.0 6.9 102 9.20 0.35
JS-W2106 2.36 0.90 212 170.0 281.0 59.7 99 19.10 0.94
JS-W2107 2.44 1.10 19 121.0 54.2 77.1 177 21.60 0.60
------------------
Sample No. Cs* La* Ce* Li* Be* Na* Mg* Al* P*
JS-W2105 4.95 12.70 24.70 32 2 8200 3700 27000 310
JS-W2106 15.30 59.10 140.50 41 9 27500 21500 80800 2470
JS-W2107 2.12 43.80 110.00 35 4 14400 5600 43800 880
------------------
Sample No. K * Ca* Sc* Ti* Te* Hf* Re* Tl*
JS-W2105 11200 6500 4.10 3500 0.71 3.40 0 1
JS-W2106 17900 36000 27.70 11050 0.37 2.90 0 1
JS-W2107 13600 12600 14.00 6220 1.22 4.80 0 1

The fact sheet was created on 01.05.2024
Questions or comments regarding the fact sheet can be emailed to:
ressursdatabaser@ngu.no
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