Cochise College          Photos of Minerals

                          Geology Home Page                

                          Roger Weller, geology instructor

                          wellerr@cochise.edu
                                  copyright 2007-R.Weller
 

Mineral Information on:
Montmorillonite


Chemical Group:  silicate- a clay mineral

Chemical Formula:  
(Mg,Ca)O.Al2O3.5SiO2.nH2O

Color: gray, greenish gray, white, yellow, yellow green, pink, brown                      Streak: white

Luster:  greasy or dull

 

Hardness:  2 to 2.5               Specific Gravity:  2.0 to 2.7                 Fracture:

Crystal Forms: Monoclinic system
     A clay mineral; crystals are exceedingly tiny.

Mineral Associations:  Bentonite is a rock made of montmorillonite

Identifying Characteristics: soapy feeling and expanding when wet

Uses: drilling mud

Occurrences:  Wyoming, Texas, and Mississippi

Toxicity:      when-swallowed- low                   when inhaled- low to moderate

Additional Information:  Montmorillonite is responsible for expanding soils which affect buildings.