What is Xieite?
Xieite is a high-pressure orthorhombic iron chromium oxide found in shocked meteorites, a polymorph of chromite formed under extreme impact conditions.
Mineralogy and structure
Reference formula: FeCr2O4. Xieite has the FeCr2O4 composition but an orthorhombic high-pressure structure distinct from ordinary cubic chromite. COD 9017077 provides an exact structural reference. Xieite is classified with oxides and has orthorhombic crystal symmetry. Typical hardness is 5–6 on the Mohs scale and specific gravity is approximately 4.7–5.0.
Colour, lustre and habit
Typical colours include black, brown-black, steel grey. The usual granular, massive, microscopic habit and metallic, sub-metallic, dull lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Xieite forms in or is associated with shock veins and high-pressure assemblages in meteorites. Important documented localities include the Suizhou meteorite in China, Yamato meteorites from Antarctica and other shocked chondrites.
A shock-forged polymorph of chromite
Xieite is valuable because it records impact pressure in the Solar System. Its structure is not a decorative variant of chromite but a mineralogical fingerprint of a meteorite shock event.
Collecting and care
Usually microscopic and embedded in meteorite material: avoid cutting or grinding, preserve the meteorite provenance and handle as a scientific specimen.
