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Formula: CsAl2(Si3Al)O10(OH)2
Phyllosilicate (sheet silicate),
dioctahedral mica group,
mica group, cesium-bearing
mineral
Crystal system: Monoclinic
Specific gravity: 3.11 measured, 3.19 calculated
Hardness: 2 to 3
Streak: White
Colour: White to silver-white
Common impurities: Mn,K,Rb,H2O
Environments
Localities
At the type locality, Pegmatite No. 31, Nanping pegmatite field, Yanping District, Nanping, Fujian, China,
nanpingite occurs as plates and scales up to 10 mm across, typically 1 to 5 mm, as radiating and comb
aggregates, rarely as pseudohexagonal crystals. White to silver-white in colour, transparent in flakes, vitreous
lustre, pearly on sheets, with a white streak. It occurs in association with
montebrasite, quartz and
apatite in veinlets up to 4 cm wide and 2 cm long in the
pollucite-rich middle zone of the
muscovite - albite -
spodumene
pegmatite
(AM 75.706-713).
Nanpingite from China - Image
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