mascagnite

{{Short description|Rare ammonium sulfate mineral}}

{{Infobox mineral

| name = Mascagnite

| image = Mascagnite-90398.jpg

| imagesize = 260px

| alt =

| caption = Acicular crystals and flakes of Mascagnite

| category = Sulfate mineral

| formula = (NH₄)₂SO₄

| IMAsymbol = Msc{{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.AD.05

| system = Orthorhombic

| class = Dipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)

| symmetry = Pnam

| unit cell =

| color = Colorless, grey, yellowish-grey, yellow

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| cleavage = Distinct/ good
On {001}

| fracture = Irregular/ uneven

| tenacity = Sectile

| mohs = 2 – {{frac|2|1|2}}

| luster = Vitreous, dull

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| diaphaneity = Transparent, translucent, opaque

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| density = 1.768 g/cm³

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| references = [https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Mascagnite Mineralienatlas][http://rruff.geo.arizona.edu/doclib/hom/mascagnite.pdf Mineral Handbook][http://www.webmineral.com/data/Mascagnite.shtml Webmineral Data][http://www.mindat.org/min-2584.html/ Mindat]

}}

Mascagnite is a rare ammonium sulfate mineral (NH₄)₂SO₄. It crystallizes in the orthorhombic system typically forming as stalactitic masses exhibiting good cleavage. It is soft (not higher than 2.5 on the Mohs scale) and water-soluble. Optical properties are variable; the purest form is transparent and colorless, but opaque gray or yellow deposits are also known.

It occurs in fumaroles, as at Mount Vesuvius and associated with coal seam fires. It was named for Italian anatomist Paolo Mascagni (1752–1815) who first described the mineral.