Cochise College          Photos of Minerals

                          Geology Home Page                

                          Roger Weller, geology instructor

                          wellerr@cochise.edu
                                  copyright 2010-R.Weller

 

Mineral Information on:
allophane

Chemical Group:   silicate

Chemical Formula:  
Al2SiO5.nH2O

Color:    pale sky blue to greenish deep green, brown , yellow, colorless                                                                   

Luster:  vitreous 6to sub-resinousStreak:

 

Hardness:     3            Specific Gravity:    1.85  and lower          

Fracture:  imperfect conchoidal, earthy

Translucent

Tenacity:  brittle

 

Habits: incrustations, mammary; waxy botryoidal to crusty masses

Mineral Associations:

Identifying Characteristics:

Uses:

Occurrences: 

Toxicity:      when-swallowed-                            when inhaled-

Additional Information: blue color is from chrysocolla
                                             brown color is from iron oxide


Allophane is a product of weathering or hydrothermal alteration of feldspar.
                  (similar to kaolinite)