letovicite

{{Short description|Ammonium sulfate mineral}}

{{Infobox mineral

| name = Letovicite

| category = Sulfate mineral

| image = Letovicite.jpg

| imagesize =

| alt =

| caption = White crystals of ammonium sulfate mineral letovicite from the Anna 2 Mine, Aachen, North Rhine – Westphalia, Germany.

| formula = (NH₄)₃H(SO₄)₂

| IMAsymbol = Let{{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 = 07.AD.20

| dana = 28.1.3.1

| system = Monoclinic

| class = Prismatic (2/m)

| symmetry = C2/c (no. 15)

| unit cell =

| color = Colorless, white

| habit = Tiny pseudo-hexagonal plates, granular

| twinning = Lamellar twinning

| cleavage = Distinct on {001}

| fracture = Uneven

| tenacity =

| mohs = 1–2

| luster =

| refractive =

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

| birefringence =

| 2V = 75° (calc.)

| pleochroism =

| streak =

| gravity = 1.83

| density =

| melt =

| fusibility =

| diagnostic =

| solubility = Soluble in water

| diaphaneity = Transparent

| other =

| references = {{cite journal |last1=Leclaire |first1=A. |last2=Ledésert |first2=M. |last3=Monier |first3=J. C. |last4=Daoud |first4=A. |last5=Damak |first5=M. |title=Structure du disulfate acide de triammonium. Une redétermination. Relations des chaînes de liaisons hydrogène avec la morphologie et la conductivité électrique |journal=Acta Crystallographica Section B: Structural Science |date=1 August 1985 |volume=41 |issue=4 |pages=209–213 |doi=10.1107/S0108768185002002|bibcode=1985AcCrB..41..209L }}

}}

Letovicite ({{IPAc-en|l|ɛ|t|oʊ|ˈ|v|ɪ|s|aɪ|t}}) is an ammonium sulfate mineral with composition (NH₄)₃H(SO₄)₂ (IUPAC: triammonium sulfate hydrogensulfate, Nickel–Strunz classification 07.AD.20).

It is a rare colorless or white monoclinic secondary mineral formed during the burning of waste coal heaps and as a deposit in hot springs. It was first described from the Letovice region of Moravia in 1932. Geologic occurrences also include Austria, Germany, Hungary, Italy, Poland, South Africa, Tajikistan and the United States.