Abstract: The study on massive hydrogrossular by means of polar microscope, infrared spectra and X ray shows that it consists mainly of hydrogrossular, with a little amount of diopside and calcite. Its refraction index is about 1. 720 and its relative density 3. 40~3.50.Point-like green about 0.1~1.0 mm in grain size is distributed in hydrogrossular and shows the shape of circle or tear. The center of point-like green consists of black point whose grain diameter is 0.01~0, 50 mm. The center of almost all point-like green consists of only one black point. The boundary between the black point and its surrounding green circle is clear. The point-like green has also a clear boundary with the hydrogrossular encircling it. Black point in green circle center is translucent under thin section by magnification 250×, transparent by magnification 400×. The result of energy spectrum analysis shows that black point consists of silicate mineral containing higher amount of iron than chlorite outside the circle. The black point results from aggregation of iron produced by chloritization of hydrogrossular. The point-like green is an important character of hydrogrossular.