Science. 1965 Jun 25;148(3678):1713-6. doi: 10.1126/science.148.3678.1713.
Carbon-rich rocks more than 2.7 billion years old, from the Soudan Iron Formation of northeastern Minnesota, contain pyrite balls in which are found microstructures of possible biologic origin. The C(13)/C(12) and S(34)/S(32) ratios and minor element composition of this rock are consistent with such an interpretation. Hydrocarbons of presumed vital origin are also present, although it is not certain that they are endemic to the rock.
富含碳的岩石有 27 亿年以上的历史，来自明尼苏达州东北部的苏德丹铁矿，其中含有黄铁矿球，其中发现了可能具有生物起源的微观结构。该岩石的 C(13)/C(12)和 S(34)/S(32)比值以及微量元素组成与这种解释一致。也存在被认为是生命起源的碳氢化合物，尽管不能确定它们是否是该岩石特有的。
