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                          Roger Weller, geology instructor

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                                  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: