Editorial Feature

Bandylite - Occurrence, Properties, and Distribution

Bandylite is a tetragonal-ditetragonal dipyramidal dark blue mineral, comprised of oxygen, hydrogen, copper, chlorine, and boron.

It was named after Dr. Mark Chance Bandy, an American mining engineer, who first discovered the mineral.

Properties of Bandylite

The following are the key properties of Bandylite:

  • Cell Data
    • Space Group: P4/n
    • a = 6.19
    • c = 5.61
    • Z = 2

  • Crystal Data
    • Tetragonal
    • Point Group: 4/m
    • As crystals, typically tabular on {001}, or pyramidal, to 5mm
    • Radial clusters, almost lichen-like, in joints in the rock

  • Chemical Composition
    Elements Content 1 Content 2
    Cu 34.94 35.73
    B2O4 23.35 24.07
    H2O 19.60 20.26
    Cl 19.47 19.94
    Na2O 0.40
    Fe2O3 0.35
    MgO 0.05
    CaO 0.05
    SO3 0.05
    insol. 1.84
    Total 100.10 100.00

  • Optical Properties
    • Optical Class: Uniaxial (–)
    • Pleochroism: Strong
    • O = deep centre blue
    • E = pale greenish-yellow
    • ω = 1.691–1.692
    • ε = 1.640–1.641

  • Estimated Properties
    Electron density Bulk density (electron density) = 2.75 g/cm3
    note: Specific gravity of Bandylite = 2.81 g/cm3
    Photoelectric PEBandylite = 16.81 barns/electron
    U = PEBandylite x ρelectron density = 46.21 barns/cm3
    Fermion index Fermion index = 0.01
    Boson index = 0.99
    Bandylite is not radioactive

How to Identify Bandylite

Bandylite can be identified by its translucent, dark blue appearance. The mineral has a vitreous luster, with a light blue streak, and cleavages. It has flexible fragments of fracture.

Density of bandylite is 2.81 g/cm3, and its relative hardness is 2.5.

Global Distribution

Bandylite is widely distributed in Chile at Quetena, west of Calama, and near Taltal, Antofagasta.

Occurrence of Bandylite and Useful Mineral Association

Bandylite occurs in a leached zone above massive iron sulfates.

It is closely associated with starkeyite, eriochalcite, and atacamite.


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