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 | |
|---|---|
| General | |
| Category | Sulfate mineral |
| Formula (repeating unit) | (NH4,K)NaSO4·2H2O |
| IMA symbol | Lcn[1] |
| Strunz classification | 7.CD.15 |
| Crystal system | Orthorhombic |
| Identification | |
| Color | Colorless |
| Cleavage | {011} Distinct [2] |
| Mohs scale hardness | 2–2.5 |
| Luster | Vitreous to dull |
| Streak | White |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 1.745 g/cc[3] |
| Density | 1.745 g/cc |
| Refractive index | nα = 1.440 nβ = 1.454 nγ = 1.455[3] |
| Birefringence | δ = 0.015[3] |
Lecontite can easily be synthesized by reacting ammonium sulfate with sodium sulfate in aqueous solution and crystallized.[6]