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 consist of hibonite. Hibonite also is a common mineral in the Ca-Al-rich inclusions (CAIs) found in some cho...
Found on http://en.wikipedia.org/wiki/Hibonite


(from the article `meteorite`) ...7,000 to 1. Types of minerals of circumstellar origin that have been isolated from chondrites include diamond, graphite, silicon carbide, silicon ...
Found on http://www.britannica.com/eb/a-z/h/46
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