Phase relation among serpentine, brucite and forsterite was examined by test-tube type hydrothermal synthetic experiments at water pressures from 200 to 500 atm. It was confirmed that the tie line change reaction curve of serpentine + brucite ←→ forsterite + water passes through the points of 200±20 atm and 310±20°C, 300±20 atm and 325±20°C, and 500±20 atm and 350±20°C.
