Cochise College          Photos of Minerals

                          Geology Home Page                

                          Roger Weller, geology instructor

                          wellerr@cochise.edu
                                  copyright 2006-R.Weller
 

Mineral Information on:
prehnite


Chemical Group:    silicate

Chemical Formula:   
H2Ca2Al2(SiO4)3

Color:  light green, white, gray      Fades on exposure to light.   

Streak:  uncolored         Luster:  vitreous          Tenacity:  brittle

 

Hardness:  6 to 6.5             Specific Gravity:     2.80 to 2.95               

Fracture:  uneven         Cleavage:  (001) distinct

 

Crystal Forms:  Orthorhombic-hemimorphic
     Crystals are rare.
     Occurs in groups of tabular crystals, reniform, globular, massive

Mineral Associations:  occurs in  cavities in basalt; found with other zeolites

Identifying Characteristics:

Uses:

Occurrences:  Massachusetts, Connecticut,  New Jersey, and Lake Superior region

Toxicity:      when-swallowed-        when inhaled-

Additional Information: