Formula: (Ca,Ce,Na)(Nb,Ta,Ti)2(O,OH,F)6
Origin of name: For A. Fersman, Russian mineralogist
Crystal system: Orthorhombic
Crystal class: 2/m 2/m 2/m
Twinning:
Unit cell:
Colour: Dark brown to black
Diaphaneity:
Luster: Subvitreous to resinous
Habit: Crystals prismatic, euhedral; granular
Hardness: 4 to 4.5
Specific gravity: 5.69 to 4.79
Cleavage: None
Tenacity:
Streak: Grayish brown
Synonyms/varieties:
Comments:
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