Mountains have frozen freshwater.
Out of all the water on Earth, saline water in oceans, seas and saline groundwater make up about 97% of it. Only 2.5-2.75% is fresh water, including 1.75-2% frozen in glaciers, ice and snow, 0.5-0.75% as fresh groundwater and soil moisture, and less than 0.01% of it as surface water in lakes, swamps and rivers.
Wikipedia, Fresh Water, 2019
Salts cannot evaporate hence cannot join the water cycle.
There is no mechanism that transports salts from seas to top of mountains. The snow on top of high mountains is actually frozen freshwater.
However 1400 years ago the Quran said that high mountains have freshwater.
[Quran 77.27] And set on it lofty mountains, and given you freshwater to drink?
How could an illiterate man who lived 1400 years ago have known that all water on top of mountains is freshwater?