Herkimer Diamonds-Negative Crystals
                        from Herkimer County, New York                                   
Cochise College
Geology Home Page 
Roger Weller, geology instructor  
Herkimer Diamonds               

last edited:  3/30/18         4 views
Photos are copyrighted by Roger Weller,
but can be used copyright-free for non-commercial educational uses.
Just credit photos to R.Weller/Cochise College.

negative crystals within Herkimer Diamonds
     There are two different types of quartz crystal-like inclusions within Herkimer
diamonds.  One type consists of hollow cavities within Herkimer diamonds that
have the shape of a quartz crystal.  Some of these cavities contain water with
bubbles and also dark impurities. Other crystal-shaped inclusions may actually
be small Herkimer diamonds enclosed within the larger crystal.  The fact that
these small crystals can be seen within the quartz is unsuspected because should
have the same index of refraction.  The fact that they can still be observed might
indicate that quartz does not have a uniform index of refraction but an index of
refraction that varies with crystal orientation.

a very good example of a negative crystal


a closer look at a well-formed negative crystal


a small crystal-like inclusion


a large, irregular inclusion and a small crystal-like inclusion