Abstract—An experimental study was carried out on the dissolution of natural octahedral diamonds from the Internatsionalnaya and Yubileinaya kimberlite pipes (Yakutia) in an Fe–S melt at 4 GPa and 1450–1500°C with different sulfur contents (10–25 wt %). It was found that with an increase in sulfur content in the iron melt, the degree of diamond dissolution sharply decreases. The stationary (final) shape of diamond crystal dissolution under the achieved conditions corresponds to an octahedroid with trigonal etching layers, which is confirmed by photogoniometry. Diamonds with similar morphology are common in kimberlite pipes, especially in mantle xenoliths from kimberlites. It was concluded that diamonds with this shape did not undergo natural dissolution in a kimberlite magma, but, similar to flat-faced octahedra, were probably isolated from it in xenoliths. Therefore, the higher the content of octahedroid-shaped diamonds with trigonal layers in a deposit, the smaller the direct influence of an aggressive kimberlite magma on the diamond content.

摘要-进行了一项实验研究，研究了从Internatsionalnaya和Yubileinaya金伯利岩管（雅库特（Yakutia））的天然八面体金刚石在4 GPa和1450-1500°C的Fe-S熔体中以不同的硫含量（10-25 wt％）的溶解情况。发现随着铁熔体中硫含量的增加，金刚石溶解程度急剧降低。在所达到的条件下，金刚石晶体溶解的静止（最终）形状对应于具有三角蚀刻层的八面体，这已通过光度法得到了证实。具有相似形态的钻石在金伯利岩管中很常见，特别是在金伯利岩的地幔异岩中。结论是，这种形状的钻石并未在金伯利岩岩浆中自然溶解，但类似于平面八面体，可能被隔离在异种石中。因此，沉积物中具有三角层的八面体形钻石的含量越高，积极的金伯利岩岩浆对钻石含量的直接影响就越小。