szomolnokite

{{Infobox mineral

| name = Szomolnokite

| category = Sulfate mineral

| image = Halotriquita i szomolnokita.png

| imagesize =

| alt =

| caption = Halotrichite (Hal); szomolnokite (Szo) and voltaite (Vol)

| formula = Fe²⁺SO₄ · H₂O

| IMAsymbol = Szo{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}

| molweight =

| strunz = 7.CB.05

| dana = 29.6.2.2

| system = Monoclinic

| class = Prismatic (2/m)

| symmetry = C2/c (no. 15)

| unit cell =

| color = Sulfur-yellow, yellow-brown, red-brown, blue, colorless

| habit = Bipyramidal, distorted, tabular, parallel growths, globular, stalactites

| twinning =

| cleavage =

| fracture = Conchoidal to sub-conchoidal, uneven

| tenacity = Brittle

| mohs = 2.5

| luster = Vitreous

| refractive =

| opticalprop = Biaxial (+), colorless (transmitted light)

| birefringence =

| 2V = 80° (measured), 86° (calculated)

| pleochroism =

| streak =

| gravity = 3.03–3.07 (measured), 3.10 (calculated)

| melt =

| fusibility =

| diagnostic =

| solubility =

| diaphaneity = Translucent

| other =

| references = {{cite journal |last1=Wildner |first1=M. |last2=Giester |first2=G. |journal=Neues Jahrbuch für Mineralogie - Monatshefte |volume=1991 |year=1991 |pages=296–306 |title=The crystal structures of kieserite-type compounds. I. Crystal structures of Me(II)SO4*H2O (Me = Mn,Fe,Co,Ni,Zn)}}

}}

Szomolnokite (Fe²⁺SO₄·H₂O) is a monoclinic iron sulfate mineral forming a complete solid solution with magnesium end-member kieserite (MgSO₄·H₂O).[http://www.mindat.org/min-3859.html Mindat.org - Szomolnokite] 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).[http://webmineral.com/data/Szomolnokite.shtml Webmineral - Szomolnokite][http://www.handbookofmineralogy.com/pdfs/szomolnokite.pdf Handbook of Mineralogy - Szomolnokite]

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

At room temperature szomolnokite is stable up to a pressure of 6.2 GPa, and then transforms into triclinic crystal structure.{{Cite journal |last1=Meusburger |first1=J. M. |last2=Ende |first2=M. |last3=Talla |first3=D. |last4=Wildner |first4=M. |last5=Miletich |first5=R. |date=2019-09-01 |title=Transformation mechanism of the pressure-induced C2/c-to-P1¯ transition in ferrous sulfate monohydrate single crystals |url=https://www.sciencedirect.com/science/article/pii/S0022459619302853 |journal=Journal of Solid State Chemistry |language=en |volume=277 |pages=240–252 |doi=10.1016/j.jssc.2019.06.004 |bibcode=2019JSSCh.277..240M |s2cid=197070809 |issn=0022-4596}}