Goethite

General

 

Category: Oxide minerals

 

Formula (repeating unit): α-FeO(OH)

 

Strunz classification: 04.FD.10

 

Identification

 

Color: Yellowish to reddish to dark brown

 

Crystal system: Orthorhombic 2/m2/m2/m

 

Cleavage: Perfect 010

 

Fracture: Uneven to splintery

 

Mohs scale hardness: 5 - 5.5

 

Luster: Adamantine to dull

 

Streak: Brown, brownish yellow to orange yellow

 

Specific gravity: 3.3 - 4.3

 

Refractive index: Opaque to sub-translucent

 

Fusibility: Fusible at 5 - 5.5

 

Other characteristics: Becomes magnetic in reducing flame

 

 

Done