Xieite, a new mineral, occurs in the shock vein of the Suizhou meteorite. The mineral has an orthorhombic structure and its
space group is
Bbmm. The cell parameters are
a = 9.462(6) Å,
b = 9.562(9) Å,
c = 2.916(1)Å. The crystal-chemical formula is (Fe
0.87Mg
0.13Mn
0.01)
1.01(Cr
1.62Al
0.25Ti
0.08V
0.02)
1.97O
4, or simply formula FeCr
2O
4. Stronger X-ray diffraction lines are [d (Å),
lll
o]: (2.675, 100), (2.389, 20), (2.089, 10), (1.953, 90), (1.566, 60), (1.439, 15), (1.425, 15), (1.337, 40). Xieite is a high
pressure polymorph of FeCr
2O
4 and formed by solid-state transformation of chromite under shock-induced high pressure and temperature, in association with
other high-pressure minerals including ringwoodite, majorite, lingunite and tuite. The
P-T condition for the formation of xieite is estimated to be 18–23 GPa and 1800–1950°C, respectively. Xieite has recently been
approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association
(IMA 2007-056). The mineral name, xieite, is named after Xiande Xie.
Keywords xieite - chromite - high-pressure - polymorph - new mineral - shock - Suizhou meteorite
Supported by National Natural Science Foundation of China (Grant Nos. 40672035 and 40272028), and the Chinese Academy of Sciences
(Grant No. KJCX2-SW-N20)