MUGNESIUM AND CALCIUM IN BERYL

摘要

Investigation of natural and synthesized berylshas shown that Ca and a part of Mg have been presented thereas inclusions of their own phases. In natural minerals calciumand magnesium generate their silicates (mica and sphene). Indry condition experiments Ca forms hydrophyllite and Mgparticipates in generating of structurally similar silicates(cordierite, beryllium indialite, beryl) and sellaite. Bycoefficients of atoms in crystallochemical formulae it has beenrevealed that magnesium has participated in natural beryls ofdifferent genesis according to the single well known scheme(1): Al~(3+)->(Mg,Fe,Mn) ~(2+)+R~+(H_2O). Into syntheticberyls Mg is introduced by the following schemes: Al_(VI)+Be_(IV)->Mg_(VI)+Al_(IV) (2)-in the form of berylliumindialite minal; 2Al_(VI)+3Be+Si -> -> 2Mg_(VI)+4Al_(IV)(3)-in composition of cordierite minal; 2Al_(VI)+Be ->Mg_(VI)+Si (4)-in composition of the 《Newtoncomponent》. The scheme (1) was realized in the syntheticberyl, as an additional one for schemes (2-4), by indroductionof Cs in the initial charges. Ca~(2+), Na~+, K~+and Rb~+ ionswere not practically entering in beryls and did not appear tocompensate a deficit of positive charges. The level ofisomorphous Mg introduction is effected by the mediaspecificity in admixtures: In the whole, there is a necessity tomake a revision of beryl compositions and to carry out somespecial experimental study of real Mg and Ca contents in this mineral.