Hydrohalite
Sodium chloride dihydrate — hydrated salt that only forms in near-freezing brines below 0.1 °C, described in 1847 from Dürrnberg, Austria.
Intro adapted from Wikipedia (CC BY-SA).
Hydrohalite is an IMA-recognized mineral species in the halide class, with the chemical formula NaCl·2H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/c).
Key properties: specific gravity 1.65; optically biaxial.
IMA symbol Hhl, grandfathered status — known before the IMA’s founding, named in 1847.
Formed from sea water or in bottom sediments of hypersaline lakes at near-freezing temperatures.
It is found associated with Halite, gypsum.
As a hydrate of halite.
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data and a Wikipedia introduction — a full written entry hasn’t been published yet.
Browse more H minerals or help write this entry.