Cochise College          Photos of Minerals

                          Geology Home Page                

                          Roger Weller, geology instructor

                          wellerr@cochise.edu
                                  copyright 2006-R.Weller
 

Mineral Information on:
olivine

Chemical Group:    silicate

Chemical Formula:   
(Mg,Fe)2SiO4


Color:  olive green, white, brown, black              Streak:  white or gray

Luster:  vitreous       Transparency:  transparent to translucent

 

Hardness:  6.5            Specific Gravity:   3.22 to 4.39                 

Cleavage: one direct, indistinct

 

Crystal Forms and Habits:  Orthorhombic system
     Olivine is commonly found in basalts as isolated crystals or granular xenoliths.

Mineral Associations:

Identifying Characteristics:

Uses:  When transparent, green, and devoid of fractures, olivine is the gemstone peridot.

Occurrences: 
Arizona famous location- Peridot on the San Carlos Indian Reservation in
     southern Arizona, about 80 miles east of Phoenix.  The olivine occurs as granular masses
     in a basalt flow perhaps 3 to 20 feet thick.  The gemmy olivine is faceted in Germany and
     Hong Kong to become the  gemstone peridot.
California:
     2 miles North of Dish Hill which is 15 miles East of Ludlow on old route 666
     between Needles and Barstow).
New Mexico:
     Portillo Maar and Kilbourne Hole, close to U.S./Mexico border, about 25 miles
     Northwest of El Paso

Toxicity:      when-swallowed- low          when inhaled- high

Additional Information:  Olivine is a mineral series that ranges from magnesium-rich (fayalite)
to iron-rich (forsterite).