Aeschynite-(Nd) is a rare earth mineral of neodymium, cerium, calcium, thorium, titanium, niobium, oxygen, and hydrogen with formula: (Nd,Ce,Ca,Th)(Ti,Nb)2(O,OH)6. Its name comes from the Greek word for “shame”. Its Mohs scale rating is 5 to 6. It is a member of the hydroxide minerals. It was named because of its similarity to aeschynite-(Ce), with neodymium as the dominant rare-earth element. It is a part of the aeschynite group.
Occurrence and Useful Mineral Association
It occurs in the veins in slate and metamorphosed dolostone. It is often associated with minerals such as aegirine, barite, fluorite, riebeckite, albite, magnetite, and phlogopite.
It was first reported for an occurrence in Bayan Obo Inner Mongolia in 1982. In that rare earth mining deposit it occurs in veins within metamorphosed dolomite and slate. It occurs associated with aegirine, riebeckite, barite, fluorite, albite, phlogopite and magnetite.
Physical Properties of Aeschynite-(Nd)
- Lustre: Adamantine
- Transparency: Transparent, Translucent
- Colour: Dark to pale brown, brownish black
- Comment: yellowish orange to reddish orange in thin section; dark grey in reflected light.
- Streak: Light yellowish brown
- Hardness: 5 – 6 on Mohs scale
- Tenacity: Brittle
- Cleavage: None Observed
- Fracture: Conchoidal
- Density: 4.6 – 5.04 g/cm3 (Measured)
Aeschynite-(Nd) can be identified by its color, brown. Its sub-translucent form has no cleavage. This mineral has an adamantine luster, with a brown streak. The fracture on this mineral is brittle–conchoidal.
The density of aeschynite-(Nd) is 4.6 to 5.04 g/cm3, with a hardness of 5 to 6 – between apatite and orthoclase.
It is distributed mainly in China – from the Bayan Obo Fe–Nb–RE deposit, 130km north of Baotou, Inner Mongolia.