Cobalt is in high demand because of the key role that cobalt-lithium-ion batteries are playing in addressing the issue of global warming, particularly in facilitating the transition from the internal combustion engine to electrically driven vehicles. Here, we review the properties of cobalt and the history of its discovery, briefly describe its mineralogy, and explore the processes that concentrate it to potentially exploitable levels. Economic cobalt deposits owe their origin to the compatible nature of Co²⁺, its concentration in the mantle in olivine, and its release, after high degrees of partial melting, to komatiitic and (to a lesser extent) basaltic magmas. Primary magmatic deposits, in which Co is subordinate to Ni, develop through the separation of immiscible sulfide liquids from mafic and ultramafic magmas and the very strong partitioning of these metals into the sulfide liquid. We evaluate the factors that concentrate cobalt to economic levels by these processes. Cobalt is also concentrated by aqueous fluids, either at ambient temperature in laterites developed over ultramafic rocks or hydrothermally in sediment-hosted copper deposits and in cobalt-rich vein deposits, where it crystallizes mainly as sulfide and arsenic-bearing minerals, respectively. Using the available thermodynamic data for aqueous Co species, we evaluate cobalt speciation as a function of temperature and show that, whereas it is transported at ambient temperature in most environments as the simple ion (Co²⁺), it is most mobile in hydrothermal systems as chloride species. Based on thermodynamic data compiled from a variety of sources, we evaluate stability relationships among some of the principal cobalt sulfide and oxide minerals as a function of temperature, pH, fO2, and α_H2S and, in conjunction with the aqueous speciation data, determine their solubility. This information is used, in turn, to predict the physicochemical conditions most favorable for cobalt transport and ore formation by hydrothermal fluids. As thermodynamic data are not available for the cobalt arsenide and sulfarsenide minerals that form the vein-type ore deposits, we use chemographic analysis to qualitatively evaluate their stability relationships and predict the physicochemical controls of ore formation. The data and interpretations of processes presented in this paper provide the theoretical basis for a companion paper in this issue in which we develop plausible models for the genesis of the principal cobalt deposit types.

中文翻译：

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钴矿床成因的限制：第一部分，理论考虑

钴的需求量很大，因为钴锂离子电池在解决全球变暖问题方面发挥着关键作用，特别是在促进从内燃机到电动汽车的过渡方面。在这里，我们回顾了钴的特性及其发现历史，简要描述了它的矿物学，并探索了将其浓缩到潜在可开采水平的过程。经济钴矿床源于 Co ^{2+的相容性}，它在橄榄石中的地幔中集中，并在高度部分熔融后释放到科马提岩和（在较小程度上）玄武质岩浆。Co 次于 Ni 的原生岩浆沉积是通过不混溶的硫化物液体与镁铁质和超镁铁质岩浆的分离以及这些金属非常强烈地分配到硫化物液体中而形成的。我们评估通过这些工艺将钴浓缩到经济水平的因素。钴也被含水流体浓缩，无论是在环境温度下在超镁铁质岩石上发育的红土中，还是在沉积物托管的铜矿床和富钴矿床中的热液中，钴主要分别结晶为硫化物和含砷矿物。使用水性 Co 物种的可用热力学数据，²⁺ )，它在热液系统中作为氯化物最容易移动。根据从各种来源收集的热力学数据，我们评估了一些主要的硫化钴和氧化物矿物之间的稳定性关系，作为温度、pH、fO2 和 α _{H 2 S的函数}并结合水性形态数据，确定它们的溶解度。反过来，该信息又用于预测最有利于钴运输和热液成矿的物理化学条件。由于没有形成脉状矿床的砷化钴和硫砷化物矿物的热力学数据，我们使用化学分析来定性评估它们的稳定性关系并预测成矿的物理化学控制。本文中提供的数据和过程解释为本期的配套论文提供了理论基础，在该论文中，我们为主要钴矿床类型的成因开发了合理的模型。