Mendozite Explained

Mendozite
Category:Sulfate minerals, alum series
Formula:NaAl(SO4)2·11H2O
Imasymbol:Mz[1]
Molweight:440.26 g/mol
Strunz:7.CC.15
Dana:29.5.4.1
System:Monoclinic
Class:Prismatic (2/m)
(same H-M symbol)
Symmetry:C2/c
Color:colorless
Habit:prismatic, pseudo-rhombohedral
Cleavage: good
indistinct
indistinct
Mohs:3
Luster:vitreous
Streak:white
Diaphaneity:transparent to translucent
Density:1.74 g/cm3
Refractive:nα = 1.449
nβ = 1.461
nγ = 1.463
Opticalprop:biaxial (-)
Birefringence:δ = 0.014
2V:56° (measured)
Solubility:soluble in water
Alteration:tamarugite
References:[2] [3] [4] [5]

Mendozite is a sulfate mineral, one of the alum series, with formula NaAl(SO4)2·11H2O. It is a hydrated form of sodium aluminium sulfate (soda alum).

It was discovered in western Argentina in 1868, probably near San Juan. The exact location has been lost, but was described as "San Juan, near Mendoza", and it is the latter city that give the mineral its name.[3] It occurs in evaporites, presumably from the oxidation of sulfide minerals in the presence of clays.[3] It is very soluble in water, and so can only be found in dry regions: however, in can still effloresce (lose water of crystallisation) in extremely arid climates, altering to tamarugite (the hexahydrate).[4]

Bibliography

Notes and References

  1. Warr. L.N.. 2021. IMA–CNMNC approved mineral symbols. Mineralogical Magazine. 85. 3. 291–320. 10.1180/mgm.2021.43. 2021MinM...85..291W. 235729616. free.
  2. https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Mendozite Mineralienatlas
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