Norsk versjon
	THE ORE DATABASE
	Deposit Area 1805 - 031
	(Last updated 23.okt.2024)

Importance

Public:

(No data)

Economical:

Not classified/evaluated

Mineralization

	Era:		Period:
	Dating:		Method:
	Genesis:		Form:
	Main texture:		Min. distribution:

Main grain size:

Main alteration:

	Strike/Dip:		Direction:
			Plunge:

Stratigraphic classification of host rock

Era:

Period:

	Province:
	Geotec.unit:
	Tectonic complex:
	Igneous complex:

Group:

Formation:

Information(s) in free text format

Free text

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

Bibliography:

From NGU's Reference Archive:

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 pages

Abstract:

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.

Fieldsamples

	Sample No.	Sample type	Miscellanrous
	28091005	Bedrock	Sampler :Axel M¿ller Comment :coarse-grained biotite granite gneiss, non-mineralised, UTM east 553636, UTM north 7558054 No. of registrated element analyses = 1 No. of registrated oxide analyses = 1

NB! All analyse values are shown at the end of the printout.:

---

Analyse Results

from

Deposit Area 1805 - 031 Hundholmen

Element analyses

( *=parts pr. million, #=parts pr.billion, Negative values means below detection limit value.)

Sample No.	Sample Type	Cu*	Zn*	Pb*	Co*	Ni*	Au#	As*
28091005	Bedrock	3	111	10	2	0	-.5	2

------------------

Sample No.	Cd*	Ba*	Mo*	Sn*	Sb*	Bi*	Se*	Ga*	V*
28091005	.1	1047	2.70	6	0	0	-0.50	26.00	-8

------------------

Sample No.	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

------------------

Sample No.	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

------------------

Sample No.	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

Oxide analyses

( All values are in % )

Sample No.	Sample Type	SiO2	Al2O3	TiO2	Fe2O3	MnO	MgO	CaO
28091005	Bedrock	67.35	14.48	0.48	4.89	0.10	0.28	2.01

------------------

Sample No.	Na2O	K2O	P2O5	Loss	Sum
28091005	3.44	5.89	0.10	0.70	100.00

---

The fact sheet was created on 22.11.2024

Questions or comments regarding the fact sheet can be emailed to: ressursdatabaser@ngu.no

Copyright © 2024 Geological Survey of Norway