Armalcolite

Armalcolite was first described from the Apollo 11 site, and is named after the Apollo 11 crew (ARMstrong, ALdrin, and COLlins). NASA lists it as a "minor" mineral.

It has since been found on Earth at a number of localities:

• Smoky Butte, Garfield County, Montana (USA) in lamproite dykes and plugs
• Disko Island (Greenland) in native iron
• Pripyat Swell (Ukraine) in trachybasalt
• South African kimberlites

Armalcolite is a part of the pseudobrookite group which consists of minerals of the general formula X₂YO₅. X and Y are usually Fe (2+ and 3+), Mg, Al, and Ti. End members are armalcolite (MgFeTi₂O₅), pseudobrookite (Fe₂TiO₅), and ferropseudobrookite (FeTi₂O₅).

Formula Weight    215.876 amu
Molar Volume      55.298 cm3/mol
Density           3.904 g/cm3
Crystal System    Orthorhombic