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	INDUSTRIMINERALDATABASEN
	Forekomstområde 1417 - 301
	(Sist oppdatert 28.okt.2024)

Betydning

Offentlig:

Regional betydning (reg. 07.02.2015)

Økonomisk:

Viktig , (Stadfestet 11.des.2001 av Havard Gautneb)

Produkt

	Element/produkt	Gehalt/Kvalitet
	SOA/TA	%

Operasjoner

	Fra - Til	Aktivitet	Kommentar
	1981 - 1990	Kjerneboring	Selskap/Institusjon:NGU & Norwegian Talc AS
	1981 - 1990	Detaljkartlegging	Selskap/Institusjon:NGU & Norwegian Talc AS
	1982 - 1983	Geofysikk	Selskap/Institusjon:NGU
	1990 - 1992	Prøvedrift	Selskap/Institusjon:Norwegian Talc AS
	1992 - 1994	Detaljkartlegging	Selskap/Institusjon:Norwegian Talc A/Norwegian Holding

Mineralisering

	Æra:		Periode:
	Datering:		Metode:
	Genese:		Form:
	Hovedtextur:		Min. fordeling:

Kornstørrelse:

	Strøk/Fall:		Retning:
			Feltstupning:

Stratigrafisk klassifikasjon av vertsbergart

Æra:

Periode:

	Provins:
	Geotek.enhet:
	Tektonisk complex:
	Intrusivt komplex:

Gruppe:

Formasjon:

Opplysning(er) i fritekstformat

Fri tekst

In 1986-1988 the Raudberget talc deposit was investigated in further details. This deposit was chosen partly because it was the deposit that was easiest and most economic to open. The Raudberget talc deposit is situated in the rim of the Raudberget ultramafite, which is dominated by antigoritic serpentinite with relics of older rocks. The talc deposit occur on the south-eastern side of the ultramafic lens and has a length of at least 500 m along strike. The north-eastern part of the talc deposit has been investigated in details by drilling. Since 1984 around 9000 m have been drilled at the deposit. The "Bottom ore", which is the lowermost ore, has a thickness of 10 - 30 m. The detailed investigated area of the Raudberget deposit was estimated to contain at least 5.27 mill. tonnes of talc-carbonate by Trønnes (1988). The "bottom ore", which was the target for the test-mining, was interpreted to contain about 70 % of this tonnage. In 1990 the Raudberget talc deposit was opened for test mining. Additional investigations were carried out by Norwegian Talc AS/Norwegian Holding in the years of 1992 and 1994. New tonnage estimations have been made later by Norwegian talc AS, but is not included here. Mineralogy The ore has the following general composition (Karlsen 1990 a): Talc (50-60 %), carbonate (40-50 %), chlorite (0-2 %), spinels (0-2 %). In addition antigorite is present in the vicinity of serpentinite bodies. In general, three types of carbonate are present: breunnerite (mostly), magnesite and dolomite. In the bottom ore, chemically zoned breunnerite and magnesite are the most common types while dolomite is seldom present. Two types of spinel are present: 1. large grains (up to 4 mm) of ferrite chromite with cores of chromite, and 2. small (up to 1 mm) grains of magnetite. The mineralogical composition depends on the structural occurrence of the sample: near the serpentinitic core the antigorite and spinel contents increase, while chlorite is slightly more abundant near the blackwall rim. Small parts of the ore are polluted by hematite giving a red colour. Table 3: Tonnage of talc-carbonate rocks in Stølsheimen as estimated by Bakke (1986 a). Deposit area Deposit Tonnage Stølsheimen Rauberget 14 000 000 Stølsheimen Lille Rauberget 23 000 000 Stølsheimen Valsvikdalen 2 700 000 Stølsheimen Bjørnshaugen 19 000 000 Comments: The geological investigations in the Stølsheimen area have proven that considerable resources are present (even if they probably are smaller that estimated). Detailed investigations by the test-mining have shown that the deposit geometry is more complex than previously known, and there are some questionmarks of the quality of the ore. Despite all the present investigations, the area has not been completely investigated and evaluated: for example, the geometry of the Bjørnshaugen and Valsvikdalen deposits is not fully understood, and a possible difference in ore quality between the deposits have not been investigated. In addition, some ultramafic bodies are present that are not described by the former investigations, although these bodies probably are much smaller. The ultramafite bearing phyllonite rock continues towards south and could carry unknown deposits. The Rauberget deposit is situated a rather long distance from the sea, and transport is both long and difficult on the present road. The county geologist of Sogn og Fjordane has recently made an idea to build a tunnel from Nærøyfjord to Framfjord. If such a plan was realised it would be important to check up the potential for deposits in the Framfjord area and the northernmost part of the Stølsheimen area. From Karlsen and Nilsson (2000).

Litteraturfortegnelser:

Fra NGU's Referansearkiv.:

Karlsen, Tor Arne; Nilsson, Lars Petter , 2000

	Talc deposits in Norway

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.99.135;146 sider

Abstrakt:

Information about talc and soapstone deposits registered in NGU's different databases and various available literature have been collected and described in the present report. Around 400 deposits/occurrences are known, but the detail of the available information varies widely. By reading old field-books as well as old manuscripts, maps, etc. dating as far back as A.D.1758, quite a lot of data has been found. The result of the work shows that most described talc in Norway is of ultramafic origin and is associated with serpentinites. The most common mineral association is talc + breunnerite. Different talc-provinces can be defined from the registered and non-registered data, the most important being Nord-Gudbrandsdalen, Altermark and Stølsheimen. While Altermark and Stølsheimen have been investgated in some detail with respect to talc as an industrial mineral, the Nord-Gudbrandsdalen talc province has been investigated both for milling talc and for soapstone use as dimension stone. Deposits that are probably extensive, but have so far not been investigated in detail, include the Lesjehorrungane deposits in the Nord-Gudbrandsdalen region and the Raudfjellet deposit in Nord-Trøndelag. The fractionated metakomatiites (pale green talc-chlorite rocks) of the southern part of the Palaeo-proterozoic Karasjok Greenstone Belt in Finnmark, Northern Norway, possibly represents, by far, the largest accumulations of talc in Norway. These rocks are recently mapped, for the first time, but other critical information is, however, very scarce.

Bakke, Stig , 1986

	Bakkemagnetometri i Raudbergfeltet

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.86.114;15 sider

Bakke, Stig , 1986

	Raudbergområdets talkpotensiale, Raudbergfeltet, Vik i Sogn

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.86.091;22 sider

Bakke, Stig , 1986

	Talk i Raudbergfeltet, Vik i Sogn

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.86.018;14 sider

Abstrakt:

Rapporten beskriver talkmineraliseringene i Raudbergfeltet, Vik i Sogn, på grunnlag av resultater fra geologisk kartlegging, magnetometri, gravimetri og diamantboriong. Feltet inneholder svært store talkmineraliseringer som er ujevnt fordelt over feltets areal. De største talkforekomstene er knyttet til spesielle foldestrukturer i de ultramafiske bergartene. Noen av de på- viste talkforekomstene er såvidt lovende at det anbefales at undersøkelsene i feltet fortsetter sommeren 1986 med detaljerte magnetiske bakkemålinger og oppboring av de mest interessante talkførende strukturene.

Bakke, Stig , 1985

	Magnesittmineraliseringer i serpentinitt fra Raudbergfeltet i Vik i Sogn

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.85.223

Abstrakt:

Under kjerneboring etter ralkforekomster i Raudbergfeltet sommeren 1984 ble det oppdaget interessante magnesittmineraliseringer i serpentinitt. BH 1C ble detaljert undersøkt med henblikk på opptreden av slike mineraliseringer. Mangesitt med mellom 1 og 2 % FeO opptrer i gehalter på ca. 20-30% i serpentinitt av betydelig mektighet som impregnasjon og stockwerk. I tillegg opptrer det endel interessante nikkelsulfidmineraliseringer i disse partiene. Det anbefales at magnesittmineraliseringene i Raudbergfeltet undersøkes videre, i første omgang ut fra eksisterende borkjernemateriale.

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