Hibonite

Hibonite Esiva eluvials, Maromby, Amboasary District, Anosy (Fort Dauphin) Region, Tul�ar (Toliara) Province, Madagascar (TYPE LOCALITY) Miniature, 3.4 x 3.4 x 2.8 cm “Courtesy of Rob Lavinsky, The Arkenstone, www.iRocks.com”

Chemical Formula: (Ca,Ce)Al12O19
Locality: Esiva, near Taolanaro (Fort Dauphin), and near Ambindandrakemba, Madagascar.
Name Origin: Named for Paul Hibon, who discovered the mineral.

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 chondritic meteorites. Hibonite is closely related to hibonite-Fe (IMA 2009-027, ((Fe,Mg)Al12O19)) an alteration mineral from the Allende meteorite.

A very rare gem, Hibonite was discovered in Madagascar by Paul Hibon, a French prospector.

Physical Properties

Cleavage: {0001} Good, {1010} Parting
Color: Black, Black, Reddish brown.
Density: 3.84
Diaphaneity: Opaque
Fracture: Sub Conchoidal – Fractures developed in brittle materials characterized by semi-curving surfaces.
Hardness: 7.5-8
Luster: Metallic
Streak: reddish brown

Photos :

Hibonite Esiva, Maromby Commune, Amboasary Department, Anosy (Fort Dauphin) Region, Madagascar (TYPE LOCALITY) Miniature, 4.0 x 3.9 x 0.8 cm “Courtesy of Rob Lavinsky, The Arkenstone, www.iRocks.com”
Hibonite Amboasary, Anosy (Fort Dauphin) Region, Tul�ar (Toliara) Province, Madagascar Cabinet, 10.3 x 7.6 x 5.0 cm “Courtesy of Rob Lavinsky, The Arkenstone, www.iRocks.com”
Vohimena deposit (Vohimena Nord), Tranomaro Commune, Amboasary District, Anosy Region (Fort Dauphin Region), Tuléar Province (Toliara), Madagascar
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