Hydrohalite is a halide mineral that occurs in saturated halite brines at cold temperatures (below 0.1 °C) and is the most common form of hydrated sodium chloride. It was first described in 1847 from an occurrence in Dürrnberg, Austria.
Physical properties
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 , solutions will normally need to be
Supercooling 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.
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),
[ reaching a maximum decomposition temperature is at 25.8°C around 9400 atmospheres. The decomposition temperature reduces again at higher pressures.][
]
Occurrence
The type locality is the Hallein Salt Mine in Austria.[Page Hydrohalite: Mineral information, data and localities on ]
Ceres
Hydrohalite was discovered on Ceres by Dawn
/ref> suggesting an early ocean, possibly surviving as a relict ocean.
