LANTHANITE

    Class : Carbonates, nitrates, borates
    Subclass : Hydrated carbonates
    Crystal system : Orthorhombic
    Chemistry : (La,Ce)2(CO3)3 8H2O
    Rarity : Rare to uncommon

Lanthanite is a group of hydrated carbonates, composed of three minerals linked together by solid solutions : lanthanite-(La), the most common mineral of the group, lanthanite-(Nd) and lanthanite-(Ce). Lanthanite-(La) is the dominant lanthanum pole, which commonly admits appreciable contents of cerium, and sometimes neodymium. It owes its name to this chemical composition. It is a rare secondary mineral present in contexts rich in rare earth elements, and as such a companion to allanite. Lanthanite forms thick lamellar to tabular crystals, more commonly colorless, white, pinkish or yellowish earthy or grainy masses.

Main photo : Lanthanite-(Ce) and malachite from Britannia Mine, Beddgelert, Gwynedd, Wales, UK © Steve Rust

Lanthanite-(Nd) from Whitianga, New-Zealand© Rod Martin
Lanthanite-(Ce) from Mosset, Pyrénées-Orientales, France © Philippe Font
Lanthanite-(Ce) from Mosset, Pyrénées-Orientales, France © Philippe Font
Lanthanite-(La) from Záluzné, Czech Republic © Jakub Jirásek (SEM image)

Lanthanite in the World

Lanthanite is known in various contexts : oxidation zones of zinc deposits (Bethlehem, Pennsylvania), allanite pegmatites (Baringer Hill, Texas), alteration of magnetite in the titanium anorthosite of Lake Sanford (New York), etc... The best samples seem to come from Bästnas (Sweden), where lanthanite-(La) encrusts cerite.

Lanthanite in France

In France, lanthanite-(Ce) is known in Mosset (Pyrénées-Orientales).

Twinning

Twins on {101} are known.

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : 2.5 to 3
Density : 2.76 to 2.84
Fracture : Irregular
Streak : White

TP : Translucent to transparent
RI : 1.520 to 1.613
Birefringence : 0.093
Optical character : Biaxial -
Pleochroism : None
Fluorescence : None

Solubility : Acids

Magnetism : NoneRadioactivity : None