Leifite has been found in a nepheline syenite pegmatite on the southeastern part of the island Vesle Arøya in the Langesundsfjord district, Norway. The mineral occurs as white to colourless fibrous masses and radiating bundles. The unit-cell dimensions are a = 14.387( 1) Å, c= 4.8734(7) Å and V= 873.6( 1) Å3. The mineral is uniaxial positive, e = 1.521( 1) and w = 1.517( 1 ). Dmeas = 2.59( l) g/cm3 . Dcalc = 2.60 g/cm3. lR spectroscopic analysis shows that leifite contains (OH) groups, but no water of crystallization as previously assumed. Wet chemical analysis gives the following empirical formula: (Na6.14Ko.92Rb0.12CS0.04Mg0.1Ca0.01 ) ?7.26Be2.07A13.04Si14.61O37.99(0H)0.97F2.04 The optical, physical and chemical data are in good agreement with previous results for the mineral. New chemical data have also been obtained for leifite from Narssårssuk, South Greenland.
A. O. Larsen & A. Åsheim, Norsk Hydro a. s. , Research Centre Porsgrunn, N-3901 Porsgrunn, Norway.