Donwilhelmsite
Donwilhelmsite is an IMA-recognized mineral species in the silicate class, with the chemical formula CaAl₄Si₂O₁₁.
It crystallizes in the hexagonal crystal system (space group P6_3/mmc).
Key properties: Mohs hardness 3.905; specific gravity 3.905.
IMA symbol Dwh, IMA status: approved, named in 2019.
Found in shock melt pockets of roughly anorthitic bulk composition in a feldspatic lunar meteorite. Formed from primordial feldspathic lunar crust during impact cratering events.
It is found associated with Ca-rich plagioclase, olivine, pyroxene, Fe-Ni metal, troilite, ilmenite, Ti-rich spinel, apatite, zircon, baddeleyite, “silica”.
The mineral was named to honor Don E. Wilhelms (b. 1930) for his seminal and ground-breaking work on the geological history of the Moon.