The crystal structure of yoderite

Abstract

Yoderite is a hydrous magnesium iron aluminosilicate discovered by D. McKie in 1956. The approximate empirical formula is [Mg2.0Ca0.~(Fe"Fe'")0.sA15.a]Si4Oi~.6(Oi)2.4. There are weak subsidiary reflections with unitary structure factors <: 0.03 (McKie, 1959). The average structure, ignoring these, has been determined and refined by two-dimensional Fourier methods. It is monoclinic with space group P21/m and cell dimensions a =8.035 _+0.003, b =5"805 _+ 0.001, c =7.346 _+0.002 A; fl = 105 38' _+4'.