The solubility was determined at temperatures from 100°C to 450°C and pressures from 1°C to 1000°C, and in solutions with NaCl concentration from 0 to 6 moles per kg H2O. Inreased pressure causes anhydrite to be more soluble at all temperatures and concentrations. The relationship between temperature and increase in NaCl concentration is more complex; solubility decreases with increasing temperature and reaches a minimum value at higher temperatures. The temperature minimum depends on the concentration of NaCl and is at lower temperatures in solutions with increased NaCl concentration. The solubility as a function of anhydrite concentration increases to a maximum, at which the concentration increases with temperature and pressure. At higher temperatures, the maxima become less pronounced. At around 180°C, solubility continuously increases at a decreasing rate as the NaCl concentration increases. At around 300°C, the solubility increases linearly with an increasing NaCl concentration, and at an increasing rate above 300°C

Generally speaking, most anhydrite-saturated solutions in nature will become undersaturated as they move away from the source and will become supersaturated as they move down. However, if the conditions change above the conditions where solubility minimums occur, then upward rising anhydrite solutions will tend to be supersaturated. For example, highly saline anhydrite solutions would be better able to precipitate at shallow depths due to changes in temperature and pressure than dilute simple water or salt solutions. For example, if the anhydrite is moving from a zone of near-impregnable rock pressure to a zone of lower pressure, such as a fracture, permeable bed or drill hole, the anhydrite may be precipitated. In general, specialised conditions are required for anhydrite to be precipitated deep in igneous rock or ore bodies

In sedimentary rocks, anhydrite could have formed in a variety of ways. Direct precipitation from sea water could have precipitated anhydrite, or externally derived solutions could have flowed through the rocks. Some anhydrite would naturally precipitate from connoisseur brines, as sediments undergo temperature and pressure changes associated with burial and lithification

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