Article · Wikipedia archive · Last revised Jul 8, 2026

Cadwaladerite

Cadwaladerite is a rare aluminium halide mineral with formula: AlCl(OH)2·4(H2O). It was reported for an amorphous substance associated with sulfate minerals and embedded in a halite crystal cluster. Its status is uncertain due to inadequate data. It was first described in 1941 for an occurrence in mine dumps of the Victoria Segunda mine Cerros Pintados, Iquique province, Tarapacá Region, Chile. It was named for Charles Meigs Biddle Cadwalader, president of the Academy of Natural Sciences. Lesukite was discredited (IMA2018-H).

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Jul 8, 2026
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Cadwaladerite
Yellow microcrystals and masses of the very rare aluminium chloride-hydroxide mineral Cadwaladerite from only one the three known localities worldwide: Maria Mine, Caleta Vítor District, Arica & Parinacota Region, Chile.
General
CategoryHalide mineral
FormulaAlCl(OH)2·4H2O
IMA symbolCwd1
Strunz classification3.BD.05
Crystal systemamorphous
Identification
Formula mass168.51 g/mol
ColorLemon yellow
FractureConchoidal
LusterVitreous
Diaphaneitytransparent
Specific gravity1.66
Optical propertiesIsotropic
Refractive indexn = 1.513, variable
Other characteristicsdeliquescent
References2345

Cadwaladerite is a rare aluminium halide mineral with formula: AlCl(OH)2·4(H2O). It was reported for an amorphous substance associated with sulfate minerals and embedded in a halite crystal cluster. Its status is uncertain due to inadequate data.345 It was first described in 1941 for an occurrence in mine dumps of the Victoria Segunda mine Cerros Pintados, Iquique province, Tarapacá Region, Chile.4 It was named for Charles Meigs Biddle Cadwalader, president of the Academy of Natural Sciences.5 Lesukite was discredited (IMA2018-H).

References

References