Mosandrite-(Ce) (original) (raw)

Formula:

(Ca3REE)[(H2O)2Ca0.5◻0.5]Ti(Si2O7)2(OH)2(H2O)2

Colour:

Deep reddish brown, brownish green, yellowish; greenish yellow

Specific Gravity:

3.2 - 3.4

Crystal System:

Monoclinic

Name:

Named as mosandrite in 1840 by Axel Joakim Erdmann in honor of the Swedish chemist and mineralogist Carl Gustav Mosander (1797-1858) who had discovered and described the element Lanthanum in 1839 (Erdmann 1840, Berzelius 1841).
Name was changed by IMA in 2016 from mosandrite to mosandrite-(Ce) (IMA 16-A).

See also rinkite-(Ce).
Mosandrite-(Ce) specimens may often shows signs of hydrothermal alteration. At the TL (Låven, Langesundsfjorden, Norway) the alteration products may be a mixture of fluorite, pyrochlore, calcite, magnetite, pyrophanite and lorenzenite (Raade 1967).

The status and definitions of the closely related Na-Ca-REE-Ti-Nb silicates of the rinkite group has been debated (Semenov 1969, Fleischer 1958, 1987): Since mosandrite has a distinctly higher H2O and lower Na content than f.ex. rinkite and nacareniobsite-(Ce), it has been suggested that mosandrite is a hydrothermal alteration of a primary rinkite phase. Fleisher (1958,1987) suggested therefore that both rinkite, and the varities of mosandrite (johnstrupite, rinkolite and lovchorrite), and calcium rinkite should all be defined as Mosandrite. However, Bellezza et al. (2009), based on thermogravity (TG), differential scanning calorimetry (DSC) and structural analysis showed that mosandrite is a distinct species, distinct from rinkite and the other valid species in the group.

Approved, 'Grandfathered' (first described prior to 1959)

IMA status notes:

Redefined by the IMA, Renamed by the IMA

IMA Formula:

(Ca3REE)[(H2O)2Ca0.5◻0.5]Ti(Si2O7)2(OH)2(H2O)2

Approval history:

2009: Redefinition of mosandrite as Ti(□,Ca,Na)3(Ca,REE)4(Si2O7)2[H2O,OH,F]4·H2O. IMA09-C
2016: Name changed from mosandrite to mosandrite-(Ce) (IMA 16-A).

Comment:

Resinous to greasy on fractures

Colour:

Deep reddish brown, brownish green, yellowish; greenish yellow

Streak:

Pale yellow, yellowish green

Cleavage:

Distinct/Good
on {100}

Fracture:

Irregular/Uneven, Conchoidal

Density:

3.2 - 3.4 g/cm3 (Measured)

Crystal System:

Monoclinic

Class (H-M):

2/m - Prismatic

Cell Parameters:

a = 7.398(1) Å, b = 5.595(1) Å, c = 18.662(2) Å
β = 101.37(1)°

Ratio:

a:b:c = 1.322 : 1 : 3.335

Morphology:

Lath-shaped, prismatic crystals, flattened on {110}, elongated along [001]

Comment:

Data from Bellezza et al. 2009, Spacegroup is P21/c

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for references and further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.