Hibonite
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Hibonite ((Ca,Ce)(Al,Ti,Mg)12O19) is a brownish black mineral 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 consists of Hibonite.
Reference
- Webmineral (http://webmineral.com/data/Hibonite.shtml)Template:Mineral-stub