| Abstrakt: |
AbstractPowder X-ray and optical data have been recorded for a sample of exceptionally rare earth-poor eudialyte (Na12(Ca, REE)6(Fe2+,Mn,Mg)3Zr3(Zr,Nb)x[Si9O27?y(OH)y]2[Si3O9]2(C1,F)z, with x = 0. 1?0.9, y = 1?3 and z = 0.7?1.4) from a pegmatitic vein associated with the peralkaline Windy Fork granite in the north?central Alaska range. The eudialyte is uniaxial positive with ?= 1.6062(2), ?= 1.6138 (3) and microprobe analyses indicate that the sum of REE + Yis less than 0.1 weight percent. Refined unit cell dimensions are: a = 14.2572(4), c = 30.1338(27), Dx= 2.67, F30= 128 (0.006, 42), M20= 76. An indexed powder diffraction pattern is given. |
