钻石瑕疵会降低珠宝成品的价值,但对地质学家来说却是宝贵的研究机会。肉眼很难发现的钻石微小瑕疵,帮助解决了地幔中存在水的长期争论。地表下400千米的地幔主要是称为橄榄石的矿物,并不吸收水。然而在此之下,高温和高压导致橄榄石变为不同的化学结构,其中之一称为尖晶橄榄石,实验室测试表明其中含有多达2.5%的水。 Diamond defects reduce the value of finished jewelery, but are valuable research opportunities for geologists. Minor imperfections in the diamond that are hard to find with the naked eye helped to solve the long-running controversy over the presence of water in the mantle. The subterranean 400-kilometer mantle is mainly a mineral called olivine and does not absorb water. However, under these conditions, high temperatures and pressures cause the olivine to change to a different chemical structure, one of which is called spinel olivine. Laboratory tests have shown that it contains as much as 2.5% water.