Gypsum Photos 
Cochise College               
Photos of Minerals
Geology Home Page

Roger Weller, geology instructor

[email protected]    copyright 2008-R.Weller
 

selenite cleavage containing inclusions
of water and gas bubbles
Penfield Quarry, New York
If a gypsum crystal (selenite) grows at a rapid rate, there may be incomplete crystal
growth resulting in the production of small cavities with the growing crystals. 
Since the material is crystalline, the cavities may take on a shape resembling the
selenite crystal; these cavities are termed "negative crystals".  Since the crystals
are being formed within a solution, small amounts of the solution along with gas
bubbles gets trapped within these cavities.
 

gypsum                                                                                                                                  bubble5
Photo is copyright free only for non-commercial educational uses.
Just credit photo to R.Weller/Cochise College.