Cebaite

Formula:  Ba₃Ce₂(CO₃)₅F₂

Origin of name:  From cerium and barium

Crystal system:  Monoclinic

Crystal class:  2/m

Twinning:

Unit cell: a = 21.4256, b = 5.0348, c = 13.2395, β = 91.613°

Colour:  Yellow to wax-yellow, orange yellow

Diaphaneity:

Luster:  Vitreous to waxy

Habit:  Granular aggregates, tabular grains

Hardness:  4.5

Specific gravity:  4.81

Cleavage:  1; {30-1} imperfect (identification uncertain)

Tenacity:

Streak:  Orange-yellow to grey-yellow, gray white

Synonyms/varieties:

Comments:  Two distinct species with the extensions -(Ce) and -(Nd) indicating the predominant rare earth cation in the formula. Nd-endmember not accepted as a valid mineral