Li 02 Feldspar Quarry (Li gruve), Li, Evje og Hornnes, Agder, Norwayi

Regional Level Types
Li 02 Feldspar Quarry (Li gruve)	Quarry
Li	Farm
Evje og Hornnes	Municipality
Agder	County
Norway	Country

This is the largest quarry in the Li pegmatite, which is the largest exposed pegmatite in the Evje-Iveland district (as far as known).

Andersen (1931) designation of the quarry: "Øvre Lie II. (Liegruben)" (p. 105).

Axel Müller of the Univeristy of Oslo describes the pegmatite exposed in the Li mine as follows:

Chemically it is a primitive (almost barren) rare-element pegmatite of the monazite and euxenite subtype with NYF affinity.

Although the pegmatite only contains a few mineral species, the mine exposes some spectacular, large-scale layered structures (line rocks) and enormous sizes of feldspar and ‘biotite’ crystals.

Emplaced in metanorite of the Iveland-Gautestad mafic intrusion (1285 ± 8 to 1271 ± 12 Ma) and banded gneisses, the Li gruve pegmatite forms an approximately 1 km long, sheet-like body striking NW-SE (Fig. 2.37).

The body varies in thickness from a few meters to 25 m, and dips at a shallow angle towards SW.

At the upper contact, there is an up to 10 cm wide medium-grained granitic border facies, which grades into wall zone (up to 2 m wide) of coarse granitic texture with plagioclase, K-feldspar and ‘biotite’.

Crystal sizes in the wall zone can reach 0.5 m. The sharp lower contact of the upper wall zone to the intermediate zone is marked by a line of megacrystic, fan-like ‘biotite’ sheets (up to 1 m in length) pointing towards the pegmatite centres forming unidirectional solidification textures (USTs) (Figs. 2.38, 2.39).

The larger ‘biotite’ sheets are bent.

The ‘biotite’-rich layer (0.5- 1 m in thickness) is followed by a layer of pinkish Kfeldspar megacrysts (0.3 to 1 m in length) with interstitial plagioclase.

These ‘biotite’-rich and K-feldspar- rich UST-layers alternate several times forming a layered line rock, in this case the intermediate zone.

The last line at the contact to the core zone is ‘biotite’-rich with fan-like ‘biotite’ up to 4 m in length.

The core zone comprises of up to 8 m long, whitish subhedral K-feldspar crystals embedded in massive quartz.

The lower intermediate zone consists also of line rock but with several differences compared to the upper intermediate zone:

(1) the layers are thinner (3 to 30cm) but higher in number;

(2) within some layers the crystals grow in two opposite directions (not only in one direction as in the upper intermediate zone);

(3) garnet,which is absent in the upper intermediate zone, is common and strongly enriched in some layers forming garnet-rich bands (Fig. 2.40).

The lower contact is not exposed.

The vertical structural zoning appears symmetrical; however, the mineralogical and chemical zoning is asymmetric in respect to ‘biotite’/garnet and K-feldspar/plagioclase ratios.

‘Biotite’ and K-feldspar are enriched in the upper wall and intermediate zone, whereas garnet and plagioclase are enriched in the lower wall and intermediate zone.

The asymmetrical zoning implies a relative low undercooling (if at all) and slow cooling rate.

The quarry is still operative, and every year 10-50 ton of high purity microcline is extracted for dental applications.

The microcline is in norwegian also called "tannspat", which translates into "tooth spar" or "dental spar".


Coordinates © Kartverket - https://www.kartverket.no

Other Regions, Features and Areas containing this locality

References