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Formula: CaSiO3
Unclassified silicate, bridgmanite subgroup
Crystal System: Isometric
Specific gravity: 4.20 calculated
Environments: Included in a diamond from a
kimberlite pipe
Davemaoite is a new mineral, approved in 2020 and to date (May 2023) reported only from the type
locality. It is an extremely high pressure mineral, formed at pressures obtaining in the lower mantle.
Localities
The type locality, the AK-8 kimberlite pipe, Orapa, Letlhakane, Central District, Botswana, is in one of the world’s
largest diamond mines Davemaoite is a
perovskite mineral that was found as an inclusion in an octahedral
diamond. The diamond was later
cut and polished to bring the inclusions closer to the surface for experimental analysis. Davemaoite occurs
with carbonaceous α-iron and
wüstite, and other inclusions in the
diamond include ilmenite,
iron, and ice-VII. Remnant pressure
in the diamond is estimated to be between 7 and 9 GPa.
The davemaoite preserved in the diamond is the first known
high-pressure silicate mineral recovered from the lower mantle. Previously, no one had observed
CaSiO3-perovskite from the lower mantle. Synthetic
CaSiO3-perovskite has been shown to lose its crystal
structure upon decompression from high pressure. The only other high-pressure silicate mineral found from
lower-mantle pressures to date was bridgmanite
(MgSiO3-perovskite) but that was found inside a meteorite.
(AM 107.778).
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