Yuzuxiangite,Sr3Fe3+(Si2O6)2(OH)·3H2O:a new inosilicate mineral
Yuzuxiangite was discovered in the Wessels Mine,Kalahari Mangnese Field,North Cape Province of Africa.It occurs as agglomerates of acicular and fiberous crystals,50-200 μm in size of the aggregate,in association with meieranite,hydroxymcglassonite-(K),sugilite,pectolite and aegirine.It has light brown color,vitreous lustre,perfect cleavages parallel to(1 0 0)and(0 0 1),an estimated Mohs hardness of 3-31/2,and the calculated desity of 3.451 g·cm-3.Under microscope of transmittance light,yuzuxiangite is observed as colorless to light yellow acicular and fiberous crystals with single crystal size less than 3 μm in diameter.It is biaxial crystal(-),α=1.66(3),β=1.68(5),γ=1.72(3)(white),2Vcal=72°.Its Raman spectrum consists of 22 peaks in 100-1500 cm-1,belonging to the Si-O,Fe-O,and Sr-O vibration modes,and 5 peaks in 1500-4000 cm-1 belonging to OH and H2O vibration modes.Its ideal formula is Sr3Fe(Si2O6)2(OH)3H2O and its empirical formula(based on cation=8)is(Sr2.94Pb0.04Ca0.02)∑3(Fe0.91Al0.09)∑1[(Si3.98 Al0.02)∑4O12](OH)3H2O.The X-ray single crystal diffraction analysis confirms that uzuxiangite belongs to the monocliniccrystal system,with cell paramters of space group P21/m,a=11.1035(10)Å,b=7.8463(7)Å,c=7.8222(7)Å,β=101.406(8)°,V=668.02(11)Å3,Z=2.The crystal structure of yuzuxiangite is same with ohmiite,characterized by a composite chain parallel to the b-axis,composed of a chain of corner-shared FeO4(OH)2 octahedra flanked by 2 parallel chains(2T4p)of comer-shared SiO4 tetrahedra,leaving the surrounding space occupied by Sr and H2O.The strongest powder X-ray diffraction lines are of d Å(I％,hkl),including 4.632(92,111),3.486(100,0 2 1),3.291(67,0 2 1),3.065(57,-2 2 1),2.841(48,3 1 1),2.118(49,3 3 0),and 1.956(46,0 4 0).Yuzuxiangite is named in honor of Prof.YU Zuxiang(1930-2019),an eminent Chinese mineralogist with important contributions to studies of new minerals,especially to studies of platinum-group element minerals in China.
yuzuxiangiteohmiliteinosilicatenew mineralKalahari manganese fieldSouth Africa
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