Science. 1967 Oct 13;158(3798):261-2. doi: 10.1126/science.158.3798.261.
Exceptionally high contents of chromium and nickel in shales from the early Precambrian Fig Tree series of South Africa ( 3.1 x 10(9) years old) suggest that the ancient crustal rocks from which these sediments were derived were ultramafic in composition.
南非早元古代 Fig Tree 系列页岩中铬和镍的含量极高，表明这些沉积物的古老地壳岩石的组成是超镁铁质的。
