Tschermigite Explained

Tschermigite
Category:Sulfate mineral
Formula:NH4Al(SO4)2·12(H2O
Imasymbol:Tmi[1])
Strunz:7.CC.20
System:Isometric
Class:Diploidal (m)
H-M symbol: (2/m)
Symmetry:Pa3 (no. 205)
Unit Cell:a = 12.215 Å; Z = 4
Color:Colorless, white; colorless in transmitted light
Habit:Octahedral crystals; fibrous columnar; powdery
Cleavage:Perfect on
Fracture:Conchoidal
Mohs: - 2
Luster:Vitreous, silky
Streak:White
Diaphaneity:Transparent to translucent
Gravity:1.645
Opticalprop:Isotropic
Refractive:1.458
Birefringence:Anomalously birefringent
Solubility:Deliquescent
References:[2] [3] [4]

Tschermigite is a mineral form of ammonium alum, formula NH4Al(SO4)2·12(H2O). It is found in burning coal seams, bituminous shale and fumaroles. Because of its extreme water solubility it is unlikely to persist except in the dryest of conditions. Discovered in 1852 at Cermiky, also known as Tschermig in Bohemia. It is colorless and named for where it was discovered.

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. http://rruff.geo.arizona.edu/doclib/hom/tschermigite.pdf Handbook of Mineralogy
  3. http://www.mindat.org/min-4036.html Tschermigite on Mindat
  4. http://webmineral.com/data/Tschermigite.shtml Tschermigite on Webmineral