Hibonite
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Hibonite is a mineral with the chemical formula Template:Chem2, 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 on Madagascar. Some presolar grains in primitive meteorites 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, Template:Chem2) an alteration mineral from the Allende meteorite.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Hibonites were among the first minerals to form as the disk of gas and dust swirling around the young sun cooled.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
A very rare gem, hibonite was discovered in 1953 in Madagascar by Paul Hibon, a French prospector.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
ColourEdit
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.<ref>Template:Cite journal</ref>