The forsterite mineral inclusions in chromite of podiform chromitite occur in mantle peridotite of Luobusa ophiolite in the Indo-Yarlung Zangbo tectonic unit. The forsterite inclusions from chromite grains have Fo number of 97~99 and assume the form of colorless, transparent and euhedral grains with abundant small faces. The crystal of forsterite used for X-ray analysis was measured to be approximately 0.15 mm×0.15 mm×0.15 mm. Crystal system of this forsterite is orthorhombic, space groupPbnm,α,βandγis 90°,a=4.7597°A,b=10.205°A,c=5.9831°A.The unit cell parameters of forsterite,a,b,cas well as M1—O and M2—O bond lengths are smaller than those of some olivines from mantle xenolith and mantle peridotites.The unit cell parameters of the forsterite in the study area are the same as those of the synthetic forsterite.According to experimental study cited in the literature, the small unit cell andcation-oxygen bond distances of olivine suggest a high pressure of its crystallization.