Hibonite gemstone

Hibonite gemstone ((Ca,Ce)(Al,Ti,Mg)12O19) is a brownish black mineral with a hardness of 7.5-8.0 and a hexagonal crystal structure.

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Hibonite gemstone

It is rare, but is found in high-grade metamorphic rocks on Madagascar. Some presolar grains in primitive meteorites. The stone also is a common mineral in the Ca-Al-rich inclusions (CAIs) found in some chondritic meteorites. The rock is closely related to hibonite-Fe (IMA 2009-027, ((Fe,Mg)Al12O19)) an alteration mineral from the Allende meteorite.

Allende meteorite

The Allende meteorite is the largest carbonaceous chondrite ever found on Earth. The fireball was witnessed at 01:05 on February 8, 1969, falling over the Mexican state of Chihuahua. After breaking up in the atmosphere, an extensive search for pieces was conducted and over 2 tonnes of meteorite were recovered

Hibonite crystal

A very rare gem, Named after Paul Hibon, a french prospector in Madagascar, who discovered the mineral in june 1953. He sent a parcel with some samples to Jean Behier for examination in the same year. Behier recognized it as a possible new mineral and gave it the working name “hibonite”.

He forwarded the sample to C. Guillemin, Labratoire de Minéralogie de la Sorbonne, in Paris, France to be further analyzed. It resulted in a description of the new mineral by Curien et al (1956).

The gemstone from Esiva, Fort Dauphin region, Tuléar, Madagascar.

Black, hard crystals suspended in metamorphosed limestone matrix rich in calcic palgioclase. Probable associates within the matrix are corundum, spinel and thorianite. Described in 1956. Not to be confused with Hibbenite. Hibonite is named after P. Hibon, who discovered the mineral.

Hibonite properties

  • Category: Oxide minerals
  • Formula: (Ca,Ce)(Al,Ti,Mg)12O19
  • Crystal system: Hexagonal
  • Crystal class: Dihexagonal dipyramidal (6/mmm)
  • H-M symbol: (6/m 2/m 2/m)


  • Color: Brownish black to black; reddish brown in thin fragments; blue in meteorite occurrence
  • Crystal habit: Prismatic platy to steep pyramidal crystals
  • Cleavage: {0001} good, {1010} parting
  • Fracture: Subconchoidal
  • Mohs scale hardness: 7½ – 8
  • Luster: Vitreous
  • Streak: reddish brown
  • Diaphaneity: Semitransparent
  • Specific gravity: 3.84
  • Optical properties: Uniaxial (-)
  • Refractive index: nω = 1.807(2), nε = 1.79(1)
  • Pleochroism: O = brownish gray; E = gray

Hibonite, from Madagascar

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