Northupite

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]

Northupite
Northupite octahedra
General
CategoryCarbonate minerals
Formula
(repeating unit)
Na3Mg(CO3)2Cl
Strunz classification5.BF.05
Crystal systemIsometric
Crystal classDiploidal (m3)
H-M symbol: (2/m3)
Space groupFd3
Unit cella = 13.98 Å; Z = 16
Identification
ColourColourless, pale yellow, grey, brown; colourless in transmitted light
Crystal habitOctahedral crystals; globular, massive
FractureConchoidal
TenacityBrittle
Mohs scale hardness3 12 - 4
LustreVitreous
DiaphaneityTransparent
Specific gravity2.380–2.407
Optical propertiesIsotropic
Refractive indexn = 1.5144 (to 1.550 with iron substitution)
SolubilityReadily soluble in dilute acids with effervescence. Decomposed by hot water with the separation of magnesium carbonate.
References[1][2][3]

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]

References


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