Taseqite

Formula: Na₁₂Sr₃Ca₆Fe₃Zr₃NbSi₂₅O₇₃(O,OH,H₂O)₃Cl₂

Origin of name: for the locality, Taseq slope, Illimaussaq complex, Greenland

Crystal system: Trigonal

Crystal class: 3m

Twinning: 

Unit cell: a = 14.286, c = 29.99

Colour: Clove brown, yellowish brown, also lemon brown

Diaphaneity: Transparent

Luster: Vitreous

Habit: Thin tabular crystals to 3 mm

Hardness: 5.5

Specific gravity: 3.24

Cleavage: 1; {0001} distinct/good

Tenacity: Brittle, conchoidal/uneven fracture

Streak: Brownish white

Synonyms/varieties:

Comments:  Member of the eudialyite group