Mica crystals from the Tourmaline Queen mine have monocrystalline muscovite cores surrounded by pinkish rims of intergrown lepidolite crystallites. The central muscovite has the 2M1 structure and is bounded by well formed {110} and {010} faces on which lepidolite has developed through epitaxial overgrowth. Lepidolite rims usually consist of lM + 2M mixtures, but one sample contained only the lM structure and had a =5.227 ± 0.002Åb= 9.020 ± 0.003Å c = 10.118 ±0.002Å, and β=100° 46' ± 1’ muscovite parameters from this crystal were a = 5.182±=0.004Å, b = 8.997 ± 0.004Å, c = 20.073± 0.007Å, andβ= 95°. 45'± 2'. Lepidolite crystallites are twinned about (310) and are attached to muscovite( 1l0) on a plane in the zone ( 110), possibly ( 110).

The lepidolite rims contain significantly more Mn, Rb, and polylithionite than the central muscovite; although outer portions of the muscovite core are slightly enriched in polylithionite, the major compositional change occurs abruptly at the interface between micas Closely associated zoned tourmaline, consisting of schorl cores surrounded by alkali tourmaline, suggests that the zoned micas were formed by crystallization from two fluids of different composition;however, polylithionite enrichment in the outermost muscovite implies that the transition between fluids may have been gradual

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