Formula: (Na,REE)15(Ca,REE)6Mn3Zr3NbSi25O74F2·2H2O
Origin of name: For Dr. C. Kent Brooks (1943-), leader of fourteen geological expeditions to the Kangerdlugssuaq area of east Greenland.
Crystal system: Trigonal
Crystal class: 3 m
Twinning:
Unit cell: a = 14.168, c = 30.0847
Colour: Yellowish brown
Diaphaneity: Transparent
Luster: Vitreous
Habit: Anhedral grains, aggregates
Hardness: 5-6
Specific gravity: 3.07-3.1
Cleavage: None
Tenacity: Brittle, uneven fracture
Streak: White
Synonyms/varieties:
Comments:
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