Cochise College          Photos of Minerals

                          Geology Home Page                

                          Roger Weller, geology instructor

                          wellerr@cochise.edu
                                  copyright 2006-R.Weller
 

Mineral Information on:
goethite


Chemical Group:    oxide

Chemical Formula:   
Fe2O3.H2O

Color:  yellowish brown, reddish brown, blackish brown

Streak:  brownish yellow to ocher yellow

 

Hardness:  5 to 5.5                 Specific Gravity:  4.28

Tenacity:  brittle           Fracture:  uneven

Cleavage:  one direction, perfect

 

Crystal Forms:  Orthorhombic system
     Crystals are rare, but occur as striated prisms.
     Goethite is commonly fibrous, foliated, reniform, stalactitic, or
     concentric with radiating structure.

Mineral Associations:  commonly found with limonite

Identifying Characteristics:

Uses:  iron ore, paint pigment

Occurrences:  Lake Superior iron district and Colorado 

Toxicity:      when-swallowed- low           when inhaled- high

Additional Information: