Abstract
Ordinary products of basic magnesium carbonate were analysed by X-ray diffractometer and the date on Hanawalt's table was supplied. The crystalline composition of them was always the same one and the lattice constants of this crystal were determined (ortho-rhombic, a=8. 34°,b=8.92A, c=I8.42°). It was found that not only the size of crystallite and the rate of crystallization increased, but also the lattice constant c decreased to 18.42° from I8.68° owing to aging of this micro crystal. And with this result, it is illustrated that the optical indexes of these products were different slightly but the chemical composition was the same.
