Unusual X-Ray Characteristics of Vermiculite from Wiry, Lower Silesia, Poland

Coarse-grained vermiculite from a serpentinite-pegmatite thermal zone displays a rational series of narrow 14.4 A basal reflections and an unusual broad 28 A peak. X-ray diffraction simulations and fitting techniques show that the 28 A peak is related to 28 A domains consisting of elongated 2:1 layers of different lengths. The domains are located at the crystal edges of the vermiculite.