Cadwaladerite - Occurrence, Properties, and Distribution

Cadwaladerite is a rare aluminium halide mineral, first described in 1941 from the Victoria Segunda mine Cerros Pintados, Iquique province in Tarapacá Region, Chile. The mineral was named after Charles Meigs Biddle Cadwalader, President of the Academy of Natural Sciences.

Properties of Cadwaladerite

The following are the key properties of Cadwaladerite:

• Cell Data
  • Space Group: n.d
  • Z = n.d

• Crystal Data
  • Amorphous
  • Point Group: n.d
  • Granular and in small masses, embedded in halite

• Chemical Composition

  Elements	Content 1	Content 2
  Al2O3	29.34	30.25
  H2O-	26.81	-
  H2O+	26.27	53.45
  Cl	21.51	21.04
  -O = Cl2	5.53	4.74
  CaO	1.60	-
  Total	100	100

• Optical Properties
  • Transparent to translucent
  • Color: Lemon-yellow
  • Luster: Vitreous
  • Optical Class: Isotropic
  • n = 1.513, variable

• Estimated Properties

  Electron density	Bulk density (electron density) = 1.73 g/cm3 note: Specific gravity of Cadwaladerite = 1.66 g/cm3
  Photoelectric	PECadwaladerite = 1.92 barns/electron U= PECadwaladerite x ρElectron density = 3.33 barns/cm3
  Fermion index	Fermion index = 0.0002 Boson index = 0.99
  Radioactivity	Cadwaladerite is not radioactive

How to Identify Cadwaladerite

Cadwaladerite is a transparent, lemon-colored mineral, having a vitreous luster. It is reported to have conchoidal fractures characterized by smoothly curving surfaces.

The density of cadwaladerite is 1.66 g/cm³.

Global Distribution

Cadwaladerite is distributed on the mine dumps at Cerro Pintados, 80km southeast of Iquique, Tarapaca, Chile.

Occurrence of Cadwaladerite and Useful Mineral Association

Cadwaladerite occurs in a sulfate deposit, embedded in halite, and is closely associated with gypsum and halite.

References

• Cadwaladerite – Mindat
• Cadwaladerite Mineral Data – Webmineral
• Cadwaladerite.pdf - Rruff Project Website - University of Arizona