The Raman spectrum of magnesite (MgCO3) has been investigated and found to be analogous in its features to that of calcite, as is to be expected in view of the similarity of structure. The frequency shifts observed are: 212 (w), 332 (st), 735 (w), 1096 (st) and 1460 (?) cm.−1 All the frequencies and especially the two lowest are notably higher than for calcite and this is explicable as due to the smaller interionic distances and correspondingly larger force constants.