Northupite, Na₂CO₃.MgCO₃.NaCl

Northupite, Na₂CO₃.MgCO₃.NaCl, occurs naturally, crystallised in the isometric system, in colourless, white, or brown crystals, with a hardness of 3.5-4 and a density of 2.38.

It has been prepared artificially by heating sodium chloride, sodium carbonate, magnesium chloride, and water in a closed flask for eight hours at 100° C. The octahedral crystals had a density of 2.377 at 15° C.; cold water decomposed them, and they melted with decomposition at a red heat.