Final answer:
In groundwater, precipitation may take place only if the mineral is undersaturated. For example, in caves, as water drips from the ceiling and the carbon dioxide escapes, the pH of the water increases and calcium carbonate crystals begin to appear, forming stalactites and stalagmites.
Step-by-step explanation:
In groundwater, precipitation may take place only if the mineral is undersaturated. This means that if the concentration of the dissolved mineral in the groundwater is lower than the solubility limit, the mineral can precipitate out of the solution and form solid crystals.
For example, in caves, as water drips from the ceiling and the carbon dioxide escapes, the pH of the water increases and calcium carbonate crystals begin to appear, forming stalactites and stalagmites.