中文摘要：

根据1975年的矿点检查报告，在大别山南部董家山蛇纹岩体的人工重砂和岩石薄片中，发现确有天然碳硅石存在。大部分碳硅石单晶为六方板状，一部分为不规则形，最大粒径450μm×100μm，一般250μm×150μm。薄片中的粒径较小。单晶的拉曼光谱位移峰值稳定，薄片中碳硅石的拉曼位移峰也都在误差范围内。单晶以二轴晶（＋）为主，部分为一轴晶（＋），薄片中晶体几乎都为二轴晶（＋）。虽然天然碳硅石可以产出于任何岩石中，但是原位的天然碳硅石只见于陨石和金伯利岩中，本文发现的很可能是首例地球蛇纹岩中的原位天然碳硅石。天然碳硅石与人工合成的碳化硅在结晶行为、光学性质和红外光谱方面有明显不同，成分也有差异，但拉曼光谱虽有差别却不明显。由于碳硅石与金刚石有类似的四面体方向sp^3异化键和相同的滑动面，可能有类似的变形条件。根据碳硅石有晶内变形，推测其形成于≥300km的深度，这对认识大别山南部构造演化有重要意义。

英文摘要：

Based on an ore-spots investigation report by No. 311 Geological Party, the authors found some natural moissanites in both artificial heavy sands and thin-sections from the Dongjiashan serpentinite in south Dabie Mountains. The single crystals from the artificial heavy sands are mostly hexagonal, partly irregular and occasionally rhombohedral. The crystals are commonly 250 μm× 150 μm in size, with the largest one being 450 μm × 100 μm. Some relatively small moissanites were found in thin sections. The Raman shifts of moissanites both as single crystals and as crystals in thin sections are typical and stable , Natural single crystal moissanites are mostly biaxial （ ＋ ）, and subordinately uniaxial （ ＋ ）. However, almost all the moissanites in thin sections are characterized by biaxial crystals （ ＋ ） With the 2E up to〉20°. Although the natural moissanites are considered to be existent in any rocks, the autochthonous natural moissanites can only be found in some kimberlites and meteorites. The moissanite reported here is probably the first occurrence in serpentinites. As both moissanite and diamond have similar tetrahedrally oriented sp^3 hybrid bonds and identical glide planes, the behavior of moissanite under stress should be comparable with that of diamond. It is thus considered that the primary moissanite might have been formed at the depth of ≥300 km, and that it is very important to understand the tectonic evolution of its host rock.