Lipscombite

Lipscombite (Fe²⁺,Mn²⁺)(Fe³⁺)₂(PO₄)₂(OH)₂^[2][3] is a green gray, olive green, or black. phosphate-based mineral containing iron, manganese, and iron phosphate.

Lipscombite
Lipscombite: Small green crystals on quartz, Harvard Museum of Natural History
General
Category	Phosphate minerals
Formula	(Fe2+,Mn2+)(Fe3+)2(PO4)2(OH)2
IMA symbol	Lcb[1]
Strunz classification	8.BB.90
Dana classification	41.10.02.01
Crystal system	Tetragonal
Crystal class	Trapezohedral (422) (same H-M symbol)
Space group	P43212
Unit cell	a = 5.37, c = 12.81 [Å]; Z = 4
Identification
Formula mass	391.27 g/mol
Color	Green gray, olive green, black.
Specific gravity	3.68
Optical properties	Translucent to opaque
References	[2][3]

Lipscombite: Small yellowish-green crystals, Lichtenberg Absetzer Mine dump, Ronneburg Uranium deposit, Gera, Thuringia, Germany

Lipscombite: Small black crystals on dark background. Smithsonian National Museum of Natural History

Lipscombite is often formed at meteorite impact sites where its crystals are microscopically small, because crystal-forming conditions of pressure and temperature are brief.

In the Classification of non-silicate minerals lipscombite is in the lipscombite group, which also includes zinclipscombite. This group is within the non-silicate, category 8, anhydrous phosphates, lazulite supergroup.

Discovery

The mineral lipscombite was first made artificially and then found in nature. It was named after chemist William Lipscomb by the mineralogist John W. Gruner who first made it artificially.^[4][5]

While investigating the stability relations of iron oxides small, black, shiny crystals were obtained when a spherical iron pressure-temperature vessel was contaminated with phosphorus.^[6] The x-ray powder diffraction pattern was similar to lazulite, but unknown.

Gruner, a mineralogist at the University of Minnesota, gave Lipscomb, a chemistry professor there, the crystals for Lewis Katz and Lipscomb to determine the atomic structure using single-crystal x-ray diffraction. They initially called the mineral iron lazulite.^[7]