Szomolnokite

Szomolnokite (Fe²⁺SO₄·H₂O) is a monoclinic iron sulfate mineral forming a complete solid solution with magnesium end-member kieserite (MgSO₄·H₂O).[1] In 1877 szomolnokite’s name was derived by Joseph Krenner from its type locality of oxidized sulfide ore containing iron in Szomolnok, Slovakia (Hungary at the time).[1][2][3]

Szomolnokite
Halotrichite (Hal); szomolnokite (Szo) and voltaite (Vol)
General
Category	Sulfate mineral
Formula (repeating unit)	Fe^2+SO4 · H2O
Strunz classification	7.CB.05
Dana classification	29.6.2.2
Crystal system	Monoclinic
Crystal class	Prismatic (2/m)
Space group	C2/c (no. 15)
Identification
Color	Sulfur-yellow, yellow-brown, red-brown, blue, colorless
Crystal habit	Bipyramidal, distorted, tabular, parallel growths, globular, stalactites
Fracture	Conchoidal to sub-conchoidal, uneven
Tenacity	Brittle
Mohs scale hardness	2.5
Luster	Vitreous
Diaphaneity	Translucent
Specific gravity	3.03–3.07 (measured), 3.10 (calculated)
Optical properties	Biaxial (+), colorless (transmitted light)
2V angle	80° (measured), 86° (calculated)
References	[1][2][3][4]

As of mid-January 2020 the only continent on which szomolnokite has not been found and reported is Antarctica.[1]

References

1. Mindat.org - Szomolnokite
2. Webmineral - Szomolnokite
3. Handbook of Mineralogy - Szomolnokite
4. Wildner, M.; Giester, G. (1991). "The crystal structures of kieserite-type compounds. I. Crystal structures of Me(II)SO4*H2O (Me = Mn,Fe,Co,Ni,Zn)". Neues Jahrbuch fur Mineralogie, Monatshefte. 1991: 296–306.

Bibliography

• Palache, P.; Berman H.; Frondel, C. (1960). "Dana's System of Mineralogy, Volume II: Halides, Nitrates, Borates, Carbonates, Sulfates, Phosphates, Arsenates, Tungstates, Molybdates, Etc. (Seventh Edition)" John Wiley and Sons, Inc., New York, pp. 479-480.