TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preparation (claimed): The magnesium aluminosilicate compound (I) is obtained by mixing silicon-containing agent, mixture of salts of magnesium, aluminum and/or element (M), and salts of element (A), (B') or (C') in a solvent, adding a precipitating agent, performing a primary heat treatment on the mixture at 800-1300 degrees C under oxidative atmosphere, and performing a secondary heat treatment at 800-1300 degrees C under a reductive atmosphere. Preferred Composition: The compound (I) is preferably of formula: ((SrsBarCat)1-x-u)(Mg1-z-v,Alz)(Si2-z,Alz)O6:(Eu2+)x,(Mn2+)y, ((CatBar)1-x-u)(Mg1-z-v,Alz)(Si2-z,Al2)O6:(Eu2+)x,(Mn2+)y, ((SrsBar)1-x-u)(Mg1-z-v,Al2)(Si2-z,Alz)O6:(Eu2+)x,(Mn2+)y, ((SrsCat)1-x-u)(Mg1-z-v,Alz)(Si2-z,Alz)O6:(Eu2+)x,(Mn2+)y, (Sr1-x-u)(Mg1-z-v,Alz)(Si2-z,Alz)O6:(Eu2+)x,(Mn2+)y, (Ba1-x-u)(Mg1-z-v,Alz)(Si2-z,Alz)O6:(Eu2+)x,(Mn2+)y or (Ca1-x-u)(Mg1-z-v,Alz)(Si2-z,Alz)O6:(Eu2+)x,(Mn2+)y. The salts are chosen from nitrate, halide, hydrosulfate and carbonate. The precipitating agent is sodium hydrogen carbonate, ammonium chloride, or ammonium hydrogen carbonate. The light source is luminescent indium-aluminum-gallium nitride.r,s,t=more than 0 to less than 1;r+s+t=1;u+v=y;v,u=more than 0;x=more than 0.1 to less than 0.3;y=more than 0.1 to less than 0.2;andz=more than 0.075 to less than 0.3. EXAMPLE - 0.0075 mole Aluminum chloride hexahydrate, 0.0200 mole calcium chloride dihydrate, 0.0463 moles silica, 0.0050 moles europium chloride hexahydrate, 0.0050 mol manganese chloride tetrahydrate and 0.0163 mole magnesium chloride tetrahydrate were dissolved in deionized water to form solution (a), and 0.5 mole ammonium hydrogen carbonate was dissolved separately in deionized water to form solution (b). The aqueous solutions (a) and (b) were simultaneously stirred into deionized water, heated at 90 degrees C, evaporated to dryness, heated at 1000 degrees C for 4 hours under oxidative atmosphere, resultant oxide material was heated at 1000 degrees C for 4 hours under reductive atmosphere, and purified, to obtain magnesium aluminosilicate compound ((Ca0.--8,Eu0.2)(Mg0.65,Mn0.2,Al0.15)(Si1.85,Al0.15)O6).