Cochise College          Photos of Minerals

                          Geology Home Page                

                          Roger Weller, geology instructor

                                  copyright 2006-R.Weller

Mineral Information on:

Chemical Group:    silicate  (plagioclase feldspar)

Chemical Formula:   
  Bytownite is a mid-composition plagioclase feldspar 
     Bytownite ranges from 30% to 10%
NaAlSi3O8 and 70% to 90% CaAl2Si2O8.

Color: white, gray, reddish, greenish, yellowish, brown, colorless       Transparency:  transparent to translucent                   

Streak:  uncolored        Luster:  vitreous, pearly        Tenacity:  brittle


Hardness:  5 to 6             Specific Gravity:  2.60 to 2.75                  

Fracture:   uneven to conchoidal

Cleavage:  (001) perfect and (010) slightly less

Crystal Forms: Triclinic system
     Crystals prismatic
     Commonly shows polysynthetic (plagioclase) twinning.

Mineral habits:  massive, granular, coarse lamellar
Mineral Associations:  igneous rocks

Identifying Characteristics:   plagioclase twinning



Toxicity:      when-swallowed- moderate              when inhaled- high

Additional Information: