Mineral wool is a man-made vitreous fiber (MMVF) manufactured mainly from igneous rocks and waste glass. Stone and glass wool, the most important mineral wools, are primarily used as thermal and acoustical insulation materials. Respirable fractions occur during handling of these materials. Thus, the inhalation of MMVF into the human respiratory system is possible. In fact, health issues are more likely to occur the longer the fibers persist. These fibers can lead to inflammation and possible formation of tumors if they do not dissolve or can be removed mechanically. Hence, fibers should easily dissolve under pulmonary conditions. There are quality labels such as the German RAL or the European EUCEB certificate which guarantee that the fibers dissolve in a short period of time and can therefore be called biosoluble. The solubility of mineral wool is linked to the chemical composition and vitreous structure. However, the dissolution mechanisms regarding mineral fibers are not known completely and the distinction between hazardous and non-hazardous mineral wool waste has significant implications for waste management. After literature research leaching behavior tests with 7 mineral wools were performed. The results of these tests were then compared to the compositions of each sample. Nearly all samples showed higher solubility results in acid conditions. In addition, the waste samples showed higher leaching results. To identify the solubility controlling mechanisms the results were modelled hydrogeochemically with the software LeachXS®. The models mainly showed the precipitation of the zeolite wairakite, the phyllosilicate magadiite and some aluminum hydroxide phases.