Original paper

Lovdarite from the Ilimaussaq alkaline complex, South Greenland

Petersen, O.V.; Niedermayr, G.; Johnsen, O.; Gault, R.A.; Brandstä tter, F.


The very rare zeolite mineral lovdarite, has been found at the Kvanefjeld Plateau in the Ilímaussaq alkaline complex, South Greenland. Here it occurs in cavities in tugtupite-bearing albitites, in association with, among other species, aegirine, albite, analcime, chkalovite, epistolite, neptunite, pyrochlore, sphalerite, tugtupite and the recently approved new mineral nabesite. The Ilímaussaq lovdarite forms fans, cockscomb to almost spherical aggregates of platy crystals, with individual crystals to 0.05×0.15×0.2mm in size. The colourless to whitish, transparent, hemihedral crystals show the forms {100}, {010} and {201}; they are platy on (100) and moderately elongated after [001]. Lovdarite from Ilímaussaq is biaxial negative with 2Vα = 60(1)°, nα = 1.5131(5), nβ (calculated) = 1.5154 and nγ = 1.5162(5), and has α = c, β = a, γ = b. The Ilímaussaq lovdarite differs from lovdarite from the type locality as far as 2V, optical sign and orientation are concerned. The unit cell parameters of the lovdarite from Ilímaussaq are: a = 39.948(4), b = 6.9407(7) and c = 7.1812(6) Å and correspond with those given for lovdarite from the type locality. The empirical formula of the Ilímaussaq lovdarite, derived from crystal structure analysis, combined with microprobe analyses, is: K3.73Na10.18Ca0.19Ba0.06(Be7.38Al0.12Si28.50O71.77)·18.39H2O.


lovdariteilimaussaq alkaline complex