Editorial Feature

Fergusonite-Beta-(Nd) – Occurrence, Properties, and Distribution

Jun 11 2014

Fergusonite-beta-(Nd) was named after the allusion to its dimorphous relationship to fergusonite-(Nd).

Properties of Fergusonite-Beta-(Nd)

The following are the key properties of fergusonite-beta-(Nd):

Cell Data
- Space group: n.d
- a = 5.07
- b = 5.62
- c = 5.41
- β = 93.0°
- Z = [2]

Crystal Data
- Monoclinic, metamict
- Point group: n.d
- As prismatic dipyramidal crystals, to 0.25mm, also as irregular grains
- X-ray powder pattern: 3.2064 (10), 3.0253 (10), 1.8832 (9), 2.7976 (5), 2.6961 (5), 2.0648 (5), 1.9549 (5)

Chemical Composition

Elements	Content 1
RE₂O₃	55.00
Nb₂O₅	41.00
UO₂	1.46
ThO₂	1.09
Ta₂O₅	0.11
SiO₂	0.29
TiO₂	0.17
ZrO₂	0.19
Al₂O₃	0.12
FeO	0.27
MnO	0.30
MgO	0.07
CaO	0.29
Total	100.36

Optical Properties
- Optical class: Isotropic to weakly anisotropic
- n = 2.0

Estimated Properties

Electron density	Bulk density (electron density) = 5.45 g/cm³ note: Specific gravity of fergusonite-beta-(Nd) = 6.16 g/cm³
Photoelectric	PE_{Fergusonite-beta-(Nd)} = 309.97 barns/electron U = PE_{Fergusonite-beta-(Nd)} x ρ electron density = 1,690.22 barns/cm³
Fermion index	Fermion index = 0.05 Boson index = 0.95
Radioactivity	Fergusonite-beta-(Nd) is radioactive

How to Identify Fergusonite-Beta-(Nd)

Fergusonite-beta-(Nd) can be identified in the field by its color variations, such as brownish-red, red, yellow-brown, and orange. Its translucent form has no cleavage. This mineral has a vitreous–greasy luster, with pale brown streak. The fracture on this mineral is brittle–sub-conchoidal.

The density of fergusonite-beta-(Nd) is 6.45 g/cm³, with a hardness of 5.5 to 6.5 - between knife blade and pyrite.

Global Distribution

Fergusonite-beta-(Nd) is distributed mainly in China, at the Bayan Obo Fe–Nb–RE deposit, 130km north of Baotou, Inner Mongolia.

Occurrence of Fergusonite-Beta-(Nd) and Useful Mineral Association

Fergusonite-beta-(Nd) occurs in sodium-metasomatised carbonatite-derived dolomitic marble.

It is often associated with minerals such as riebeckite, ferroan dolomite, biotite, magnetite, pyrite, monazite, bastnasite, aeschynite-(Nd), ilmenite, fergusonite-(Ce), and fergusonite-(Nd).