lecontite

{{Infobox mineral

| name = Lecontite

| category = Sulfate mineral

| boxwidth =

| boxbgcolor =

| image =

| imagesize =

| caption =

| formula = (NH₄,K)NaSO₄·2H₂O

| IMAsymbol = Lcn{{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.CD.15

| system = Orthorhombic

| class =

| symmetry =

| color = Colorless

| habit =

| twinning =

| cleavage = {011} Distinct

| fracture =

| mohs = 2–2.5

| luster = Vitreous to dull

| refractive = nα = 1.440 nβ = 1.454 nγ = 1.455{{cite web

| title = Lecontite

| url = https://www.mindat.org/min-2364.html

| work = Mindat

}}

| opticalprop =

| birefringence = δ = 0.015

| pleochroism =

| streak = White

| gravity = 1.745 g/cc

| density = 1.745 g/cc

| melt =

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| diagnostic =

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| diaphaneity = Transparent to translucent

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}}

Lecontite (sodium ammonium sulfate dihydrate, with potassium substituting for some ammonium, typically about a fourth{{cite web

| url = http://webmineral.com/data/Lecontite.shtml

| title = Lecontite Mineral Data

| work = Webmineral

| accessdate = 2022-04-15

}}) is a sulfate mineral with the formula (NH₄,K)NaSO₄·2H₂O. It was found by John Lawrence LeConte in Las Piedras Cave in Honduras as a breakdown product of bat guano, including crystals up to an inch long and identified as a separate mineral by W.J. Taylor in 1858.{{cite journal

| first = W.J.

| last = Taylor

| title = Lecontite, a new mineral

| journal = American Journal of Science and Arts

| volume = 76

| pages = 273–274

| year = 1858

}} As of 1963 most natural specimens came from the same cave.{{cite journal

| title = X-ray study of lecontite

| first1 = Robert J.

| last1 = Faust

| last2 = Bloss

| first2 = F. Donald

| journal = American Mineralogist

| year = 1963

| volume = 48

| issue = January–February

| pages = 180–188

| url = https://pubs.geoscienceworld.org/msa/ammin/article-abstract/48/1-2/180/542037/X-ray-study-of-lecontite

}}

Lecontite can easily be synthesized by reacting ammonium sulfate with sodium sulfate in aqueous solution and crystallized.{{cite web

| url = https://dmishin.github.io/crystals/sodium-ammonium-sulfate.html

| title = Sodium ammonium sulfate

| work = DmiShin home, crystal growing collection

| first = Dmitry

| last = Shintyakov

| accessdate = 2022-04-15

}}