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	MALMDATABASEN
	Forekomstområde 1805 - 031
	(Sist oppdatert 23.okt.2024)

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Müller (2011) writes the following: The Hundholmen pegmatite is a granitic pegmatite which was mined from 1906 up to around 1970 for feldspar, some quartz and fluorite. The fluorite is enriched in Y and Ce in the form of yttrofluorite, cerfluorite and fluocerite (Husdal 2008). Common REE-Th-U minerals of the Hundholmen pegmatite are allanite, bastnäsite-(Ce), columbite-(Fe), euxenite-(Y), fluocerite- (Ce), fluorapatite, fluorite, fluorthalénite-(Y), fergusonite-(Y), gadolinite-(Y), hingganite-(Y), hundholmenite-(Y), monazite, synchysite, tengerite-(Y), thalénite-(Y), thorite, uraninite, xenotime, zircon. With respect to REE, Y, Th and U mineralisations the exploited pegmatite has no economic potential. However, the host granite of the Hundholmen pegmatite is described as grey, medium- to coarse-grained biotite-amphibole alkali granite with very common allanite and titanite (Vogt 1922). The amphibole is hastingsite – a Na-Ca amphibole. Whole-rock analyses of this granite are not reported. Due to its mineralogical description, the host granite of the Hundholmen pegmatite may have elevated REE concentration, therefore, the area was suggested as target area in the NGU report 2009.037. The pegmatite and the Hundholmen area were visited together with Tore Vrålstad and Ola Torstensen, chief geologist of the Nordland county (Fig. 37). First, the waste heap of the former pegmatite mine was examined. Several large pieces of greenish white fluorite were found (Fig. 38). The fluorite can hardly be distinguished from quartz. The most distinguishing feature is the hardness. Semi-quantitative EDX analyses revealed that the fluorite contains less than 1 wt.% REE. However, the fluorite contains common inclusions of a Y-Ca-silicate which could not be identified (Fig. 39a). Less common are gadolinite inclusions which occur together with muscovite crystals in the fluorite (Fig. 39b). The host, coarse-grained granite gneiss close to the pegmatite had very low gamma-ray intensity of 250 cps. In addition the rocks of the outcrop were weathered and leached by sea water. It was decided to take a fresh granite gneiss sample from a road cut about 2 km SE of the pegmatite (Fig. 37a). At the road cut (33V 0553636/7558054) the granite gneiss had a gamma radiation intensity of 550 cps. The analysis revealed 0.062 wt.% REO+Y2O3, 665 ppm Zr, 24 ppm Th and 7 ppm U (Fig. 40, Appendix 2). LREE and in particular HREE are enriched compared to average granite composition (Fig. 41). An interesting feature is the weaker Eu anomaly compared to the other Tysfjord granites. The reason for the strong HREE enrichment is the high abundance of zircon, reflected by the high Zr concentration. Because of the low radiation intensity, SEM examination was not carried out on the sample

Litteraturfortegnelser:

Fra NGU's Referansearkiv.:

Müller, Axel , 2011

	Potential of rare earth element and Zr-, Be, U-, Th-, (W-) mineralisations in central and northern Nordland - Part 2

;Norges geologiske undersøkelse;RAPPORT;NGU-rapport; No.2011.021;56 sider

Abstrakt:

In this report results of the investigation of potential rare earth elements (REE) and Zr-, Be, U-, Th-, (W-) mineralisations in central and northern Nordland are presented. The investigated and sampled mineralisations were proposed in NGU report 2009.037 on the basis if existing reports and geochemical data sets. The investigation targets were evolved Proterozoic TIB-type granites (TIB = Trans-Scandinavian Igneous Belt) of the Tysfjord, Sommerset and Rishaugfjell basement windows, in particular, the Hatten- Tilthornet massif, Hundholmen, Kjerrfjellet, Hellemobotn, Reinoksskardet, upper Gjerdalen areas, the Sommerset basement Window, Rismålsvatn, and Memaurvatn. The general aim was to identify Zr-Ree mineralisations with >= 2wt.% REO (including Y2O3; REO - rare earth oxides) which are possibly enriched in Be, U and Th as well.

Feltprøver

	Prøvenr.	Prøvetype	Diverse
	28091005	Fastfjell	Prøvetaker :Axel M¿ller Kommentar :coarse-grained biotite granite gneiss, non-mineralised, UTM east 553636, UTM north 7558054 Antall registrerte elementanalyser = 1 Antall registrerte oksydanalyser = 1

NB! Alle analyseverdier er vist i slutten av utskriften.:

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Analyseresultater

fra

Forekomstområde 1805 - 031 Hundholmen

Elementanalyser

( *=parts pr. million, #=parts pr.billion, Negative verdier betyr under deteksjonsgrensen.)

Prøvenr.	Prøvetype	Cu*	Zn*	Pb*	Co*	Ni*	Au#	As*
28091005	Fastfjell	3	111	10	2	0	-.5	2

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Prøvenr.	Cd*	Ba*	Mo*	Sn*	Sb*	Bi*	Se*	Ga*	V*
28091005	.1	1047	2.70	6	0	0	-0.50	26.00	-8

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Prøvenr.	Th*	U*	W*	Rb*	Sr*	Y*	Zr*	Nb*	Cs*
28091005	21.40	7.10	1	251.4	173.3	86.7	665	41.80	3.20

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Prøvenr.	La*	Ce*	Pr*	Nd*	Sm*	Eu*	Gd*	Tb*	Dy*
28091005	75.90	186.40	21.34	82.70	15.83	1.95	13.18	2.33	13.71

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Prøvenr.	Ho*	Er*	Tm*	Yb*	Lu*	Be*	Hf*	Hg*	Tl*
28091005	2.83	8.54	1.35	9.40	1.47	6	18.10	-0	1

Oksydanalyser

(Alle verdier er i %)

Prøvenr.	Prøvetype	SiO2	Al2O3	TiO2	Fe2O3	MnO	MgO	CaO
28091005	Fastfjell	67.35	14.48	0.48	4.89	0.10	0.28	2.01

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Prøvenr.	Na2O	K2O	P2O5	Loss	Sum
28091005	3.44	5.89	0.10	0.70	100.00

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Faktaarket ble generert 22.11.2024

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