Efremovite Explained

Efremovite
Category:Sulfate minerals
Formula:(NH4)2Mg2(SO4)3
Imasymbol:Efr[1]
Strunz:7.AC.10
System:Cubic
Class:Tetartoidal (23)
H-M symbol: (23)
Unit Cell:a = 9.99 Å; Z = 2
Color:White to gray
Habit:Equant grains and crusts
Cleavage:None
Fracture:Uneven
Mohs:2
Luster:Vitreous
Diaphaneity:Transparent to nearly opaque
Gravity:2.52 (calculated)
Opticalprop:Isotropic
Refractive:n = 1.550
Alteration:Readily hygroscopic
References:[2]

Efremovite is a rare ammonium sulfate mineral with the chemical formula: (NH4)2Mg2(SO4)3. It is a white to gray cubic mineral.[3] This anhydrous sulfate occurs as constituent in sulfate crusts of burning coal dumps. It is hygroscopic and when exposed to humid air it slowly converts to the hydrate form, boussingaultite.[4] [5]

It was first described in 1989 for an occurrence in the Chelyabinsk coal basin, Southern Urals, Russia. It was named for Russian geologist Ivan Antonovich Yefremov (1907–1972). It has also been reported from several coal mining areas across Europe. It occurs in association with native sulfur,, mascagnite, and boussingaultite.[3]

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://webmineral.com/data/Efremovite.shtml Efremovite
  3. http://rruff.geo.arizona.edu/doclib/hom/efremovite.pdf Handbook of Mineralogy
  4. Chesnokov B. V. and Shcherbakova E. P. 1991: Mineralogiya gorelykh otvalov Chelyabinskogo ugolnogo basseina - opyt mineralogii tekhnogenesa. Nauka, Moscow
  5. Jambor J. L. and Grew E. S. 1991: New mineral names. American Mineralogist, 76, pp. 299-305