* Dissolving is a chemical process where the bonds holding the mineral's crystal structure together are broken, and the individual ions or molecules become surrounded by the solvent molecules. Think of salt dissolving in water: the sodium and chloride ions separate and are surrounded by water molecules.
* Evaporation is a physical change where a liquid transitions into a gas due to an increase in temperature. The molecules gain enough energy to overcome their attractive forces and escape into the atmosphere.
* Melting is a physical change where a solid transitions into a liquid due to an increase in temperature. The molecules gain enough energy to overcome their rigid structure and move freely.
In short: Dissolving involves breaking chemical bonds, while evaporation and melting involve changes in physical state.
