Chloritoid is a silicate mineral of metamorphic origin. It is an iron magnesium manganese alumino-silicate hydroxide with formula (Fe, Mg, Mn)
2Al
4Si
2O
10(OH)
4. It occurs as greenish grey to black platy micaceous crystals and foliated masses. Its Mohs hardness is 6.5, unusually high for a platy mineral, and it has a specific gravity of 3.52 to 3.57. It typically occurs in phyllites, schists and marbles.
Both monoclinic and triclinic polytypes exist and both are pseudohexagonal.[2][3]
It was first described in 1837 from localities in the Ural Mountains region of Russia. It was named for its similarity to the chlorite group of minerals.[3][4]
References
- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ a b Handbook of Mineralogy
- ^ a b c Mindat
- ^ a b Webmineral data
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