Black crystal of the extremely rare K-Cr oxide mineral yimengite from the type locality in Yimeng Mountains, China, and only one of the very few known localities worldwide. Probably analyzed by the former owner of the specimen (the Vandenbroucke Museum, but the analysis is no longer available). Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Yimengite
Yimengite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula K[Ti₃Cr₅Fe³⁺₂Mg₂]O₁₉.
It crystallizes in the hexagonal crystal system (space group P6_3/mmc). It is a member of the Magnetoplumbite structural group.
Key properties: Mohs hardness 4.1; specific gravity 4.34; Brown streak; Metallic luster; optically uniaxial.
IMA symbol Yim, IMA status: approved, named in 1982.
A metasomatic alteration product of chromian spinel in kimberlites.
It is found associated with Chromian spinel, mathiasite, olivine, phlogopite, pyrope, chromite, ilmenite, chromian diopside, apatite, zircon, moissanite, perovskite (Yimeng Mountain area.
The name refers to its occurrence in the Yimeng Mountain area, China.