Lazurite

Lazurite
Lazurite
	Lazurite, Ladjuar Medam (Lajur Madan; Lapis-lazuli Mine), Sar-e-Sang District, Koksha Valley (Kokscha; Kokcha), Badakhshan (Badakshan; Badahsan) Province, Afghanistan
General
Category	Tectosilicate
Formula; (repeating unit)	(Na,Ca)8[(S,Cl,SO4,OH)2\|(Al6Si6O24)]
IMA symbol	Lzr
Strunz classification	9.FB.10
Crystal system	Isometric
Crystal class	Hextetrahedral (43m) ; H-M symbol: (4 3m)
Space group	P43n
Unit cell	a = 9.09 Å; Z = 2
Identification
Color	Deep blue, azure, violet-blue, greenish blue
Crystal habit	Crystals occur as dodecahedra, or rarely cubes; granular, disseminated, or massive
Cleavage	Imperfect on {110}
Fracture	Uneven
Tenacity	Brittle
Mohs scale hardness	5–5.5
Luster	Vitreous
Diaphaneity	Translucent to opaque
Specific gravity	2.38–2.45
Optical properties	Isotropic; anomalously anisotropic
Refractive index	1.502–1.522
Fusibility	3.5
Solubility	Soluble in HCl
References

Lazurite is a tectosilicate mineral with sulfate, sulfur and chloride with formula (Na,Ca)₈[(S,Cl,SO₄,OH)₂|(Al₆Si₆O₂₄)]. It is a feldspathoid and a member of the sodalite group. Lazurite crystallizes in the isometric system although well‐formed crystals are rare. It is usually massive and forms the bulk of the gemstone lapis lazuli.

^ 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
^ Mindat with location data
^ Webmineral data
^ Hurlbut, Cornelius S. and Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., Wiley, p. 459 ISBN 0-471-80580-7
^ "Mineralogical Society of America" (PDF). Archived from the original (PDF) on 2016-03-03. Retrieved 2011-03-08.

[1] 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.

[HBM-2] Handbook of Mineralogy

[Mindat-3] Mindat with location data

[Webmin-4] Webmineral data

[Klein-5] Hurlbut, Cornelius S. and Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., Wiley, p. 459 ISBN 0-471-80580-7

[6] "Mineralogical Society of America" (PDF). Archived from the original (PDF) on 2016-03-03. Retrieved 2011-03-08.

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