Cochise College          Photos of Minerals

                          Geology Home Page                

                          Roger Weller, geology instructor

                          wellerr@cochise.edu
                                  copyright 2006-R.Weller
 

Mineral Information on:
hornblende

Chemical Group:    silicate-amphibole group

Chemical Formula: 
NaCa2(Mg,Fe,Al)5(Si,Al)8O22(OH)2   

Color:  dark green, dark brown, black             Streak:  white to gray

Luster:  vitreous

 

Hardness:  6       Specific Gravity:  3.0 to 3.4                

Cleavage:  2 directions at an angle of 124 degrees from each other

 

Crystal Forms and Habits:  Monoclinic system
     Hornblende forms prismatic crystals

Mineral Associations:  diorites, syenites and is common in medium grade metamorphic rocks.

Identifying Characteristics:  elongated crystals, dark color, cleavage angles

Uses:

Occurrences: 

Toxicity:      when-swallowed- low             when inhaled- high

Additional Information: