Hibonite

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