Cochise College          Photos of Minerals

                          Geology Home Page                

                          Roger Weller, geology instructor

                                  copyright 2006-R.Weller

Mineral Information on:

Chemical Group:   silicate    

Chemical Formula: 

Color:  pale gray, gray, yellowish brown, greenish gray, apple-green, peach-blossom red, rose red

Streak: uncolored 


Hardness:  6 to 6.5        Specific Gravity:  3.25 to 3.37

Fracture:  uneven to sub-conchoidal          Transparency:  transparent to sub-translucent

Luster:  vitreous     Tenacity:  brittle

Cleavage:  (010) perfect


Crystal Forms: Orthorhombic system
     prismatic crystals; rarely withy terminations 

Mineral habits:  massive, columnar, compact

Mineral Associations:  red corundum (rubies) 

Identifying Characteristics:  green color (massive) with rubies

Uses:  rarely as a gemstone, carvings  

Occurrences:   Africa 

Toxicity:      when-swallowed-                            when inhaled-

Additional Information: