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: asparagus green, grass-green, emerald-green, greenish white,  yellowish green,
        brownish green, red                  

Fracture:   uneven to subconchoidal 


Hardness:     8.5         Specific Gravity:   3.5 to 3.84           

Cleavage:  (011) distinct, (010) imperfect          Luster:   vitreous

Tenacity:  brittle                 Streak:  uncolored

Transparency:  transparent to translucent


Crystal Forms: Orthorhombic system
     Commonly forms twins; twins often are pseudo-hexagonal.

Mineral Associations:  found in granites, pegmatites, and mica schists

Identifying Characteristics:

Uses:  gemstone (alexandrite)

Occurrences:  Ural Mountains; also Maine, Connecticut, and New York 

Toxicity:      when-swallowed-        when inhaled-

Additional Information:  Alexandrite is green under sunlight, but red in artificial light