For magnesium, it can be seen that the initial range cannot be represented by a regression. This is shown by the parameter 𝐶 0,𝑀𝑔,𝑖 , which has a value greater than the measured amount of magnesium in distilled water in all series of measurements. For all values greater than 0 h, the measuring points can be approximated using equation (6). Therefore, a mathematical definition of the whole leaching process is necessary. The initial range up to 1 h can be described linearly, while the time steps > 1 h can be modeled with the same approach as for calcium. When comparing 𝐶 ∞,𝑀𝑔,𝐴𝑛ℎ𝑦𝑑𝑟𝑖𝑡𝑒 during the leaching of magnesium from anhydrite, the value increases for higher stoichiometric ratios. The rate 𝑘 𝑀𝑔,𝐴𝑛ℎ𝑦𝑑𝑟𝑖𝑡𝑒 decreases with increasing acid concentration. In contrast, the other two parameters, 𝐶 ∞,𝑀𝑔,𝐴𝑛ℎ𝑦𝑑𝑟𝑖𝑡𝑒 and 𝐶 0,𝑀𝑔,𝐴𝑛ℎ𝑦𝑑𝑟𝑖𝑡𝑒 , increase in the same ratio, which explains the similar Mg 2+ concentrations up to 8 h. Overall, therefore, the leaching of Mg 2+ is not directly dependent on the amount of acid. Talc leaching shows an increase in rate 𝑘 𝑀𝑔,𝑇𝑎𝑙𝑐 and concentration at steady state 𝐶 ∞,𝑀𝑔,𝑇𝑎𝑙𝑐 . This shows a dependence on acid concentration and pH. Firstly, a higher proportion of magnesium is leached from the particles and secondly, the reaction proceeds faster. Both 𝐶 ∞,𝑀𝑔,𝑇𝑎𝑙𝑐 and 𝑘 𝑀𝑔,𝑇𝑎𝑙𝑐 increase linearly with stoichiometry. ) as a function of the stoichiometric ratio 𝑆𝑡. The upper part shows the leaching of calcium from Figure (left)Figure and the lower part shows the leaching of magnesium from Figure (right).