What type of temperature changes produce large crystals

Temperature has a clear effect on the growth rate of salt crystals. If you carry out an experiment with salt solutions, one at room temperature, one at a colder temperature and one at a warmer temperature, you see that the warm temperature sample grows crystals faster than both the other samples, and the room temperature sample grows faster than the cold sample. This is because a higher temperature increases the rate of evaporation of the solvent, thereby speeding up the rate of growth. Different temperatures produce different amounts of crystals. Colder solutions contract, forcing minerals closer together, so they create bonds, catching impurities in their structure at the same time. These impurities interrupt the crystal pattern, forming a larger number of smaller crystals. In warmer temperatures, the distance between molecules is greater, which allows crystals to form larger, purer shapes at a much more uniform rate than can occur at colder temperatures.

Anions are negative charged ions