Lecontite (

sodium Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable iso ...

ammonium sulfate dihydrate, with potassium substituting for some ammonium, typically about a fourth) is a sulfate mineral with the formula (NH₄,K)NaSO₄·2H₂O. It was found by

John Lawrence LeConte John Lawrence LeConte (May 13, 1825 – November 15, 1883) was an American entomologist of the 19th century, responsible for naming and describing approximately half of the insect taxa known in the United States during his lifetime,

in Las Piedras Cave in

Honduras Honduras, officially the Republic of Honduras, is a country in Central America. The republic of Honduras is bordered to the west by Guatemala, to the southwest by El Salvador, to the southeast by Nicaragua, to the south by the Pacific Oce ...

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. As of 1963 most natural specimens came from the same cave. Lecontite can easily be synthesized by reacting ammonium sulfate with

sodium sulfate Sodium sulfate (also known as sodium sulphate or sulfate of soda) is the inorganic compound with formula Na2SO4 as well as several related hydrates. All forms are white solids that are highly soluble in water. With an annual production of 6 milli ...

in aqueous solution and crystallized.

References

Ammonium minerals Sodium minerals Sulfate minerals Orthorhombic minerals {{sulfate-mineral-stub, In particular, I don't know anything about crystallography or optics, and Dmitry Shintyakov has licensed the photos of his synthetic lecontite specimens (see refs) under CC0 according to https://dmishin.github.io/about.html.