Sewardite

Formula CaFe2(AsO4)2(OH)2

Origin of name: For Terry Maxwell Seward (1940-) who collected the mineral.

 

Crystal system: Orthorhombic

Crystal class: 2/m 2/m 2/m

Twinning: 

Unit cell: a = 16.461, b = 7.434, c = 12.131

 

Colour: Dark red, ligher red orange

Diaphaneity: Translucent

Luster: Vitreous

Habit: Platy, anhedral grains, in aggregates

Hardness: 3.5

Specific gravity

Cleavage: 2: [100] imperfect, [011] imperfect

Tenacity: Splintery fracture

Streak: Reddish brown

 

Synonyms/varieties:

 

Comments: 

 

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