Northupite is an uncommon evaporite mineral, with the chemical formula Na3Mg(CO3)2Cl. It occurs as colourless to dark grey or brown octahedral crystals and as globular masses. In synthetic material it forms a series with tychite
It was discovered in 1895 at Searles Lake , San Bernardino County by C. H. Northup (born 1861) from San Jose, California , for whom Northupite is named.
It occurs associated with tychite, pirssonite at Searles Lake and with shortite , pirssonite, gaylussite, norsethite and quartz of Wyoming