STUDY OF MINERALOGY CHARACTERISTICS OF MICROCRYSTAL MUSCOVITE FROM WEST SICHUAN

Micro-crystal muscovite in west Sichuan is a new kind of muscovite resource.The main chemical compositions of micro-crystal muscovite are SiO_2 45.7%,Al_2O_3 30.51%,K_2O(11.63%,)H_2O 4.53%,similar to the theoretic value of muscovite chemical compositions.The main impure ions,such as Fe,Mg~(2+) etc.,replace Al~(3+) in octahedral of the micro-crystal muscovite.Micro-crystal muscovite presents a tiny-thin plate shape.Diameter of crystalline grains are less than 10 μm and most of them range from 1 μm to 5 μm,with an averge value of 5.4 μm.The averge value of crystalline grains thickness is 0.8 μm and the ratio of diameter/thickness of micro-crystal muscovite is 6.9.It characterized by high crystallinity and low degree of hydration.There is no montmorillonite interlayer in micro-crystal muscovite.The lattice parameters are a=0.520 01 nm,b=0.906 33 nm,c=2.003 96 nm,α=90.00°,β=95.79°,γ=90.00°,which belongs to 2M_1 type muscovite.These show the difference in structure mineralogy between micro-crystal muscovite and sericite.