Thermodynamics of the natural assemblages of Ni-Co-Mn-Cu-Fe-Zn arsenates

拟议工作的第一个目标是确定来自贾奇莫夫的选定次生矿物的合成类似物的热力学性质。这些矿物是：i)德国矿族矿物[M(AsO_3OH)·H_2O矿物，M=Mn、锌、Co、镁、钙或钙/锰]，II)镁铝矿族砷酸盐[M_3(AsO_4)_2·8H_2O，其中M=Ni、Co、锌、镁、锰、铁和铜]，以及III)酸性砷酸铁-硫酸盐钾盐[Fe(AsO_2(OH)_2)·5H_2O]和闪锌矿[Fe_2(AsO_4)(SO_4)(OH)·5H_2O]。从这些组中挑选出的矿物将被合成，它们的热力学性质将通过量热技术的组合来确定。这一选择是基于对历史悠久的Ag-Ni-Co-U(As-As-Bi)矿床Jáchymov(Joachimsthal)地下空间的实地考察。历史悠久的Ag-Ni-Co-U(As-As-Bi)矿床Jáchymov的地下空间提供了一个具有许多当地环境的天然实验室，我们在之前的工作中进行了调查。在拟议工作中获得的数据将被用来理解次生矿物的形成并对其进行数值模拟。该项目的第二个目标是扩大次生矿物的大型热力学数据集在0-200摄氏度之间的适用范围。这项工作将通过组合德拜-爱因斯坦函数对现有数据集进行拟合，使用适当的软件(SUPCRT)计算不同温度下的溶解度常数并将结果制表来实现。这项工作将允许整个地球化学界使用这些数据来模拟涉及许多次生砷酸盐、硫酸盐或氧化物的任何过程。

The first goal of the proposed work is the determination of thermodynamic properties of synthetic analogs of selected secondary minerals from Jáchymov. These are i) minerals of the krautite group [M(AsO3OH)·H2O minerals with M = Mn, Zn, Co, Mg, Ca, or Ca/Mn], ii) arsenates of the vivianite group [M3(AsO4)2·8H2O, where M = Ni, Co, Zn, Mg, Mn, Fe, and Cu], and iii) acidic ferric arsenate-sulfates kaatialaite [Fe(AsO2(OH)2)·5H2O] and sarmientite [Fe2(AsO4)(SO4)(OH)·5H2O]. Selected minerals from these groups will be synthesized and their thermodynamic properties determined by a combination of calorimetric techniques. The selection is based on the field work in the underground spaces in a historical Ag-Ni-Co-U(-As-Bi) ore deposit Jáchymov (Joachimsthal). The underground spaces of the historical Ag-Ni-Co-U(-As-Bi) deposit Jáchymov offer a natural laboratory with many local environments which we investigated in our previous work. The data obtained within the proposed work will be used to understand and numerically model the formation of the secondary minerals.The second goal of the project is the extension of applicability of a large thermodynamic data set for secondary minerals for temperatures between 0-200 oC. This work will be achieved by fitting the already existing data sets by a combination of Debye-Einstein functions, calculating the solubility constants at various temperatures using the appropriate software (SUPCRT) and tabulating the results. This work will allow the entire geochemical community to use the data to model any process involving many secondary arsenates, sulfates, or oxides.