Shen Mengmeng, Lu Zhiyun, Xu Yan, He Xuemei
School of Gemmology, China University of Geosciences, Beijing 100083, China.
State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China.
ACS Omega. 2021 Aug 17;6(34):22284-22291. doi: 10.1021/acsomega.1c02964. eCollection 2021 Aug 31.
The phase composition and distribution characteristics have been obtained from two mammoth ivory samples with typical blue and yellowish-brown outer layers. The results reveal that hydroxyapatite, newberyite, organic matter, and quartz exist in all structures of mammoth ivory. Vivianite and santabarbaraite mainly contribute to the blue and yellowish-brown oxide layers of mammoth ivory, respectively. Meanwhile, metavivianite also occurs and partly influences the appearance of oxide layers. Vivianite is a common and complex product that can be formed by the interaction of gradually infiltrated Fe and the original PO in mammoth ivory. At the later stage, vivianite can be oxidized into metavivianite and santabarbaraite. As a result, mammoth tusks present dark bluish-green and yellowish-brown appearances. The multi-colored oxide layers are formed by different contents of vivianite and its oxidation products, which also provides valuable information on the relative burial intensity and time in different structures. It is inferred that the burial intensity increases in the sequence of yellowish-white dentin → blue outer layer → yellowish-brown outer layer. These observations are hopeful to be widely used in evaluating the changeable burial environment and exploring historical events that occurred on mammoth ivory.
从两个具有典型蓝色和黄褐色外层的猛犸象牙样本中获得了相组成和分布特征。结果表明，猛犸象牙的所有结构中均存在羟基磷灰石、磷铁石、有机物和石英。蓝铁矿和磷锌矿分别主要促成了猛犸象牙的蓝色和黄褐色氧化层。同时，变蓝铁矿也存在并部分影响氧化层的外观。蓝铁矿是一种常见且复杂的产物，可由猛犸象牙中逐渐渗入的铁与原始磷酸根相互作用形成。在后期，蓝铁矿可氧化为变蓝铁矿和磷锌矿。结果，猛犸象牙呈现出暗蓝绿色和黄褐色外观。多层彩色氧化层由不同含量的蓝铁矿及其氧化产物形成，这也为不同结构中的相对埋藏强度和时间提供了有价值的信息。据推断，埋藏强度按黄白色牙本质→蓝色外层→黄褐色外层的顺序增加。这些观察结果有望广泛应用于评估多变的埋藏环境以及探索猛犸象牙上发生的历史事件。
