Editorial Feature

Balangeroite – Occurrence, Properties, and Distribution

Jun 13 2014

Balangeroite was named by after the Balangero mine in Piedmont, Italy.

Properties of Balangeroite

The following are the key properties of balangeroite:

Cell Data
- Space group: P2/n
- a = 19.40
- b = 9.65
- c = 19.40
- β = 91.1°
- Z = [2]

Crystal Data
- Monoclinic
- Point group: 2/m
- Fibrous, both loose and compact
- Asbestiform, elongated along [001], to several cm
- X-ray powder pattern: 2.714 (100), 6.77 (80), 2.674 (75), 3.378 (45), 9.59 (40), 3.278 (40), 2.516 (40)

Chemical Composition

Elements	Content 1
MgO	31.81
SiO₂	28.37
FeO	16.95
Fe₂O₃	8.89
H₂O	[9.93]
MnO	3.59
Al₂O₃	0.27
CaO	0.13
Cr₂O₃	0.03
TiO₂	0.03
Total	[100.00]

Optical Properties
- Optical class: Biaxial (-)
- Pleochroism: Distinct; dark brown || [001]; yellow-brown ⊥ [001]
- Orientation: X = a; Y = c; Z = b
- α = 1.680(5) ⊥ [001]; β = n.d; γ = ~1.680 || [001]
- 2V(meas.) = n.d

Estimated Properties

Electron density	Bulk density (electron density) = 3.01 g/cm³ note: Specific gravity of balangeroite = 3.03 g/cm³
Photoelectric	PE_Balangeroite = 7.38 barns/electron U = PE_Balangeroite x ρ electron density = 22.18 barns/cm³
Fermion index	Fermion index = 0.02 Boson index = 0.98
Radioactivity	Balangeroite is not radioactive

How to Identify Balangeroite

Balangeroite can be identified in the field by its color variations, such as brownish-yellow, and dark brown. Its subtranslucent to opaque form has very good cleavage. This mineral has a vitreous-greasy luster, with brownish-white streak.

The density of balangeroite is 2.96 to 3.1 g/cm³.

Global Distribution

Balangeroite is distributed mainly in Italy, in the Balangero (San Vittore) mine, and at Ponte del Diavolo, Lanzo Valley. It is also distributed from Santa Maria della Neve in Fiano, Piedmont.

Occurrence of Balangeroite and Useful Mineral Association

Balangeroite occurs in schistose serpentinite in proximity to a large ultramac massif.

It is often associated with minerals such as magnetite, Fe-Ni alloy, olivine, chlorite, chrysotile, titanian clinohumite, diopside, antigorite, aragonite, opal, calcite, chalcedony, and clay minerals.