Hapkeite
An iron silicide found in a lunar meteorite recovered in Oman — a fragment of the Moon's highland breccia.
Intro adapted from Wikipedia (CC BY-SA).
Hapkeite is an IMA-recognized mineral species in the native element class, with the chemical formula Fe₂Si.
It crystallizes in the cubic crystal system (space group Pm3m).
Key properties: specific gravity 6.83; Metallic. R: (470) 47.1, (546) 48.8, (589) 50.0, (650) 50.9 luster; optically isotropic.
IMA symbol Hpk, IMA status: approved, named in 2003.
Found in a highland regolith breccia clast in the lunar meteorite Dhofar 280, formed by impact-induced, vapor-phase deposition under extreme reducing conditions in lunar soil.
It is found associated with FeSi (fersilicite and ferdisilicite), vitrified plagioclase (“maskelynite”), FeNi.
The mineral was named to honor Bruce Hapke (emeritus, University of Pittsburgh), who first predicted the presence of vapor-deposited elemental Fe as coatings on lunar soil grains.