One of the most important factors that affect geochemical processes involving the formation and transformation of mineral deposits is their solubility. Water collects minerals from various sources and carries them along side while travelling through different layers, finally depositing them through various physico-chemical processes viz. preferential precipitation, co-precipitation or evaporation over a long period of time. Thus,
Nitrates are highly soluble in water. If found on tropical regions of Earth, they would dissolve in rainwater and wash into the oceans. Therefore, they are found only in areas where the possibility of leaching is very low, i.e. places of low rainfall, like deserts.
The high solubility of sodium, chloride, and sulfate ions results in them dissolving and flowing into the world’s oceans. Finally they get deposited in there, and concentrated layers of mineral deposits result over millions of years.