Lecontite
General
CategorySulfate mineral
Formula
(repeating unit)		(NH4,K)NaSO4·2H2O
IMA symbolLcn[1]
Strunz classification7.CD.15
Crystal systemOrthorhombic
Identification
ColorColorless
Cleavage{011} Distinct [2]
Mohs scale hardness2–2.5
LusterVitreous to dull
StreakWhite
DiaphaneityTransparent to translucent
Specific gravity1.745 g/cc[3]
Density1.745 g/cc
Refractive indexnα = 1.440 nβ = 1.454 nγ = 1.455[3]
Birefringenceδ = 0.015[3]

Lecontite (sodium ammonium sulfate dihydrate, with potassium substituting for some ammonium, typically about a fourth[2]) 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[3] 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]

References

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ a b "Lecontite Mineral Data". Webmineral. Retrieved 2022-04-15.
  3. ^ a b c d "Lecontite". Mindat.
  4. ^ Taylor, W.J. (1858). "Lecontite, a new mineral". American Journal of Science and Arts. 76: 273–274.
  5. ^ Faust, Robert J.; Bloss, F. Donald (1963). "X-ray study of lecontite". American Mineralogist. 48 (January–February): 180–188.
  6. ^ Shintyakov, Dmitry. "Sodium ammonium sulfate". DmiShin home, crystal growing collection. Retrieved 2022-04-15.


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