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Occurence 4613 - 004 Bømlo
(Object Id: 4732)
(Last updated: 08.11.2016)

Location
County: Vestland Municipality: Bømlo (4613)
Map 1:50000: Bømlo (1114-2) Map 1:250000: Haugesund
Coordinate system: EU89-UTM Zone 32
East: 284217 m. North: 6624741 m.
Longitude: 5.1641240 Latitude: 59.7044840
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Resource
Resource Type: Precious metals (Au,Ag,PGE) Resource Subtype: Gold
Element(s): Au
Importance
Raw material meaning: Little Importance (reg. 26.05.2015)

Resources and production
Activity: Test mining Reserves:
Operating method: Open pit and underground mining Historical production:


Operations
From - To Activity Comments
1890 - 1891 Test mining
1984 - 1984 Core drilling Company/Institution :NGU

Mineralization
Genesis: Hydrothermal vein Form: Plate
Main texture: Vein network Min. distribution: Disseminated (<20 % ore minerals)
Main grain size: Fine grained (< 1 mm) Main alteration: Chloritisation
Strike/Dip: 100 / 80 Direction:
Plunge:
Stratigraphic classification of host rock
Era: Period:
Province: Caledonides
Geotec.unit: Hardangerfjord Nappe Complex
Tectonic complex:
Igneous complex: Lykling Ophiolite Complex
Group: Formation:

Mineralogy
Relationship Mineral Amount
Gangue mineral Quartz Major mineral (>10%)
Gangue mineral Carbonate Subordinate mineral (1-10%)
Gangue mineral Chlorite Subordinate mineral (1-10%)
Ore mineral Gold Accessory mineral (<1%)
Ore mineral Chalcopyrite Accessory mineral (<1%)
Ore mineral Pyrite Accessory mineral (<1%)

Lithology:
Relationship Rock Origin
Unknown Gabbro Intrusive
Original rock :Gabbro
535 (-46\+46) mill. years
Metamorphic facies :Greenschist

Structures
Location: Type: Orientation(360 gr.): Relation to min.:
Unknown Shear plane Strike/Dip :100 / 80 Syn-mineralisation

Information(s) in free text format
Free text
The Bømlo deposits are mesothermal gold-bearing quartz veins in shear zones in the Lykling ophiolite complex, frequently following the contacts of dolerite dykes. The veins and their chloritised and carbonatised wallrocks are characterized by the presence of coarse-grained native gold, giving spectacular hand specimens that are extracted today. Analyses of bulk samples are normally in the range of 2–5 g/t Au. A few, minor Cu-Zn and Fe-sulphide (‘vasskis’) occurrences are related to metabasalts and felsic metavolcanic rocks overlying the ophiolite complex

Bibliography:
From NGU's Reference Archive:
Amaliksen, Knut Gunnar , 1984
Gullforekomster på Bømlo, Diamantboringer.
;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.84.016;14 pages
Abstract:
I rapporten framlegges borlogger med analyseresultater fra diamantboringene (Pack-Sack) på Haugesundsgangen og Harald Haarfagres gang, (to av Lyklingområdets) gullførende kvarts/skiferganger. Rapporten framlegges som et tillegg til NGU-rapport nr. 1750/35A. Borkjernene viser at mineraliseringen stort sett kun er knyttet til selve kvarts/skifergangene. Følgelig er malmvolumet lavt og av begrenset økonomisk intresse.

Wulff, Peter Wilhelm , 1996
En befaring af cirka 100 mineraliseringer i Sunnhordland, SV-Norge
;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.96.139;100 pages
Abstract:
Forfatteren var sommeren 1994 engasjert av NGU for å gjøre et arbeid i Sunn- hordland i forbindelse med planlagt utgivelse av en publikasjon om Norges gullforekomster. Samtidig kunne Malmdatabasen gjøres ferdig for dette området. Rapporten beskriver resultatene av malmregistrering i Sunnhordland som om- fatter ca. 100 mineraliseringer. Disse er koordinatfestet og geologisk beskrevet. I tillegg er det gitt gruvehistoriske kommentarer av forekomstene og referanser. Resultatene fra denne rapport er innlagt i NGUs Malmdatabase. Rapporten gis av praktiske grunner ut i dansk språkform som den foreligger fra forfatter.

Wulff, P.; Stendal, H. , 1995
Gold in Sunnhordland, the caledonides of southwestern Norway. [Abstract]
;Grønlands geologiske undersøgelse;ARTIKKEL;Open file series; Gold mineralization in the Nordic countries and Greenland. Extended; abstracts; No.95/10;116-119 pages
Abstract:
Conclusion The Palaeozoic supracrustal rocks of the Sunnhordland area is an important metallogenic zone with gold-bearing quartz veins and massive sulfide mineralization especially Cu and Zn associated with Au and Ag. The gold mineralization in most of the quartz veins is of the mesothermal type. Wulff (1993) and Christensen (1994) concluded that most quartz veins on Bømlo are spatially related to the Sunnhordland Fault Zone (SFZ) or the Hardangerfjord Fault Zone (HFZ). The quartz veins at Vernøy and Hovdaneset is situated not far from SFZ or HFZ thus indicating a relationship. In summary this study has shown that far from all interesting mineralization has been found in the highly prospective Sunnhordland area. The most prospective areas is considered to be along SFZ and HFZ.


The fact sheet was created on 24.10.2021

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