From Wikipedia, the free encyclopedia
Jump to: navigation, search
Northupite octahedra
Category Carbonate minerals
(repeating unit)
Strunz classification 5.BF.05
Crystal system Isometric
Crystal class Diploidal (m3)
H-M symbol: (2/m3)
Space group Fd3
Unit cell a = 13.98 Å; Z = 16
Colour Colourless, pale yellow, grey, brown; colourless in transmitted light
Crystal habit Octahedral crystals; globular, massive
Fracture Conchoidal
Tenacity Brittle
Mohs scale hardness 3½ - 4
Lustre Vitreous
Diaphaneity Transparent
Specific gravity 2.380–2.407
Optical properties Isotropic
Refractive index n = 1.5144 (to 1.550 with iron substitution)
Solubility Readily soluble in dilute acids with effervescence. Decomposed by hot water with the separation of magnesium carbonate.
References [1][2][3]

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 (Na6Mg2(CO3)4SO4).[2]

It was discovered in 1895 at Searles Lake, San Bernardino County, California 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, trona, pirssonite, gaylussite, labuntsovite, searlesite, norsethite, loughlinite, pyrite and quartz in the Green River Formation of Wyoming.[1]