Cochise College          Photos of Minerals

                          Geology Home Page                

                          Roger Weller, geology instructor

                                  copyright 2006-R.Weller

Mineral Information on:

Chemical Group:    carbonate

Chemical Formula:   

Color:  white, gray, yellow, green, pink, red, violet

Streak:  white         Transparency:  transparent to translucent


Hardness:  3.5 to 4        Specific Gravity:  2.93 to 2.95

Fracture:  subconchoidal                  Luster:  vitreous to resinous

Cleavage:  two directions


Crystal Forms and habits:  Orthorhombic system
     Aragonite is commonly acicular (see cave formations).
     Another common form is a pseudo-hexagonal plate produced by twinning.

Mineral Associations:

Identifying Characteristics:  Fizzes with hydrochloric like calcite


Occurrences:  Bisbee, Arizona (acicular) and Ft. Collins, Colorado (hexagonal twins)

Toxicity:      when-swallowed- low            when inhaled- low

Additional Information:  Aragonite is less stable than calcite and will often revert to calcite.