Humite

Humite
Humite
	Humite specimen, Italy
General
Category	Nesosilicates
Formula	(Mg,Fe)7(SiO4)3(F,OH)2.
IMA symbol	Hu
Strunz classification	9.AF.50
Crystal system	Orthorhombic
Crystal class	Dipyramidal (mmm) ; H–M Symbol: (2/m 2/m 2/m)
Space group	Pbnm
Unit cell	a = 10.24, b = 20.72 ; c = 4.73 [Å]; Z = 4
Identification
Color	White, yellow, dark orange, brown
Cleavage	Poor
Fracture	Uneven to subconchoidal
Tenacity	Brittle
Mohs scale hardness	6–6.5
Luster	Vitreous
Streak	White
Diaphaneity	Transparent
Specific gravity	3.20 – 3.32
Optical properties	Biaxial (+)
Refractive index	nα =1.607–1.643, nβ=1.619–1.653, nγ=1.639–1.675
Birefringence	0.0320
2V angle	Calculated = 70–78°, measured = 68–81°
Dispersion	Weak, r > v
References

Humite is a mineral found in the volcanically ejected masses of Vesuvius. It was first described in 1813 and named for Abraham Hume (1749–1838).^[5]

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.
^ Handbook of Mineralogy
^ Webmineral data
^ Mindat w/ locations
^ Deer, W.; Howie, R.; Zussman, J. (1997). Rock-forming Minerals: Volume 1A, Second Edition, Orthosilicates. Bath, UK: The Geological Society. ISBN 1-897799-88-8.

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