Mindat Logo

Hamilton possible polydymite

Posted by Timothy Greenland  
avatar Hamilton possible polydymite
February 25, 2012 07:02PM
Are there any Hamilton fans that could help me with this specimen? I got it by exchange back in 1964 from WB Sanborn of San Francisco with the label "Millerite in Calcote, Hamilton, Hancock Co. Illinois, U.S.A.". I was always intrigued by the curvy needles of the included material, as all the millerite I knew was basically straight - with occasional deviation... On looking at the Mindat page for Hamilton, I saw the pictures of polydymite in calcite which look very like my piece. Can anyone give me an informed opinion???

Ist photo: Overall view with centimeter scale. the largest calcite crystal (essentially two nail-head terminations without prism) is a bit over 2 cms across. The colour is not quite right - the background should be pure white.

2nd photo - close-up of the included needles FOV ca 5mm. Stack of 5 through-focus views. The double refraction of the calcite causes some of the deeper hairs to form double images.

Any comments will be most welcome



Your Email:


  • Valid attachments: jpg, gif, png, pdf
  • No file can be larger than 1000 KB
  • 3 more file(s) can be attached to this message

Spam prevention:
Please, enter the code that you see below in the input field. This is for blocking bots that try to post this form automatically. If the code is hard to read, then just try to guess it right. If you enter the wrong code, a new image is created and you get another chance to enter it right.
Mineral and/or Locality  
Search Google  
Copyright © Jolyon Ralph and Ida Chau 1993-2014. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of thousands of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
Current server date and time: December 18, 2014 21:01:07
Mineral and Locality Search
and/or Locality:
Fade toolbar when not in focusFix toolbar to bottom of page
Hide Social Media Links
Slideshow frame delay seconds