Hibonite is a mineral with the chemical formula , occurring in various colours, with a hardness of 7.5–8.0 and a hexagonal crystal structure. It is rare, but is found in high-grade
metamorphic rocks
Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...
on
Madagascar
Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...
. Some
presolar grains
Presolar grains are interstellar solid matter in the form of tiny solid grains that originated at a time before the Sun was formed. Presolar stardust grains formed within outflowing and cooling gases from earlier presolar stars.
The stellar nuc ...
in primitive
meteorites
A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet or moon. When the original object en ...
consist of hibonite. Hibonite also is a common mineral in the
Ca-Al-rich inclusions found in some
chondritic meteorites. Hibonite is closely related to hibonite-Fe (IMA 2009-027, ) an alteration mineral from the
Allende meteorite
The Allende meteorite is the largest carbonaceous chondrite ever found on Earth. The fireball was witnessed at 01:05 on February 8, 1969, falling over the Mexican state of Chihuahua. After it broke up in the atmosphere, an extensive search for ...
. Hibonites were among the first minerals to form as the disk of gas and dust swirling around the young sun cooled.
A very rare gem, hibonite was discovered in 1953 in Madagascar by Paul Hibon, a French prospector.
Colour
Hibonite can vary in colour, from a bright blue, to green, to orange, to a nearly black deep brown. The colour is related to the degree of oxidation; meteoritic hibonite tends to be blue.
See also
*
Glossary of meteoritics
This is a glossary of terms used in meteoritics, the science of meteorites.
#
* 2 Pallas – an asteroid from the asteroid belt and one of the likely parent bodies of the CR meteorites.
* 4 Vesta – second-largest asteroid in the asteroid b ...
References
Webmineral
Calcium minerals
Lanthanide minerals
Aluminium minerals
Oxide minerals
Meteorite minerals
Hexagonal minerals
Minerals in space group 194
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