Lecontite Explained

Lecontite
Category:	Sulfate mineral
Formula:	(NH4,K)NaSO4·2H2O
Imasymbol:	Lcn^[1]
Strunz:	7.CD.15
System:	Orthorhombic
Color:	Colorless
Cleavage:	Distinct
Mohs:	2–2.5
Luster:	Vitreous to dull
Refractive:	nα = 1.440 nβ = 1.454 nγ = 1.455^[2]
Birefringence:	δ = 0.015
Streak:	White
Gravity:	1.745 g/cc
Density:	1.745 g/cc
Diaphaneity:	Transparent to translucent

Lecontite (sodium ammonium sulfate dihydrate, with potassium substituting for some ammonium, typically about a fourth^[3]) 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.^[4] As of 1963 most natural specimens came from the same cave.^[5]

Lecontite can easily be synthesized by reacting ammonium sulfate with sodium sulfate in aqueous solution and crystallized.^[6]

Notes and References

1. Warr. L.N.. 2021. IMA–CNMNC approved mineral symbols. Mineralogical Magazine. 85. 3. 291–320. 10.1180/mgm.2021.43. 2021MinM...85..291W. 235729616. free.
2. Web site: Lecontite . Mindat.
3. Web site: Lecontite Mineral Data . Webmineral . 2022-04-15.
4. W.J.. Taylor. Lecontite, a new mineral. American Journal of Science and Arts. 76. 273–274. 1858.
5. X-ray study of lecontite. Robert J.. Faust. Bloss. F. Donald. American Mineralogist. 1963. 48. January–February. 180–188.
6. Web site: Sodium ammonium sulfate. DmiShin home, crystal growing collection. Dmitry. Shintyakov. 2022-04-15.