Barioperovskite,
ideally BaTiO3, is a new member of the
perovskite group. It is found as micro- to nano-crystals in a host of
amorphous material contained within hollow, tubular inclusions in
benitoite from the Benitoite Mine, San Benito County, California,
U.S.A. The mean chemical composition determined by electron-microprobe
analysis is (wt%) BaO 65.46, TiO2 34.57, SiO2
0.89, sum 100.92. The empirical formula calculated on the basis of 3 O
is Ba0.97Ti0.98Si0.03O3.
Barioperovskite is orthorhombic, Amm2; a = 3.9874 Å, b =
5.6751 Å, c = 5.6901 Å, V = 128.76 Å3,
and Z = 2. The electron backscattered diffraction pattern is an
excellent match to that of synthetic BaTiO3
with the Amm2 structure. The strongest calculated X-ray powder
diffraction lines from the synthetic BaTiO3
data are [d in Å, (I), hkl] 4.018 (18) (011), 2.845 (30)
(002), 2.830 (100) (111), 2.316(20) (102), 2.312 (23) (120), 2.009 (28)
(022), 1.640 (17) (113), 1.637 (19) (131), 1.633 (18) (202), and 1.415
(15) (222). The mineral is named after its composition, a Ba-dominant
member of the perovskite group.