The negative striations and micromorphology of pyrite crystals on a {210} face in the auriferous quartz vein were studied by means of differential interference microscope，SEM and TEM. The{210} faces of pyrite crystals are F-faces，which have developed free growth layers. The mechanism of their crystal growth is controlled by two-dimensional nucleation and layer-by-layer growth. Both simple pentagonal dodecahedron habit and other morphology of pyrite crystals develop free growth layers on the {210} faces. Some positive striations on the {210} faces are formed by piling up of steps of growth layers on the {100} faces, and other positive striations on the {210} faces are formed by piling up of steps of growth layers on the {210}faces. Transmission electron observation reveals that crystals with negative striation are formed through auto-epitaxial settlement of block nuclei 30～50 nm in diameter on growing crystals. Electronic diffraction pattern shows that the single block nuclei consist of many minute crystallites already formed in the solution. This suggests that these crystals have been grown in a reasonable environment characterized by very high super-saturation and low gradient of temperature. Their growth is not related to impurity. Based on an analysis of PBC theory and Donnay-Hark law, we can rea-sonably interpret the phenomenon why free growth layers are commonly seen on the {100} faces but are rarely developed on the {210} faces of pyrite crystals in nature. Besides occurring in the Shakanai mine of Japan, the pyrite crystals with negative striations are also developed in gold deposits of quartz-sulfide veins