Hydrohalite

Hydrohalite has a high nucleation energy, it decomposes at 0.1°C, giving a salty brine and solid halite.

The cryohydric point of hydrohalite is at −21.2 °C (−6.2 °F), solutions will normally need to be supercooled for crystals to form. Above this temperature, liquid water saturated with salt can exist in equilibrium with hydrohalite. Unlike halite, hydrohalite has a strong positive temperature coefficient of solubility.^[2] Under pressure, hydrohalite is stable between 7,900 and 11,600 atmospheres pressure. The decomposition point increases at the rate of 0.007K per atmosphere (for 1–1000 atmospheres),^[2] reaching a maximum decomposition temperature is at 25.8°C around 9400 atmospheres. The decomposition temperature reduces again at higher pressures.^[2]

The type locality is the Hallein Salt Mine in Austria.^[3]

Hydrohalite was discovered on Ceres by Dawn,^[4] suggesting an early ocean, possibly surviving as a relict ocean.

• Hydrohalite Mineral Data