Mindat Logo
bannerbannerbannerbanner
Welcome!

Unknown from Ojuela Mine, Mexico

Posted by Robert Simonoff  
avatar Unknown from Ojuela Mine, Mexico
February 26, 2012 01:13AM
    
This was gotten in Tucson this year. The dealer did not know what the black mineral was, but insisted that it was the matrix and should not be looked at. The only thing on this piece worth looking at is the hemimorphite on the other side. The dealer actually took it and turned it back the "right" way. Well,, it seems pretty nice this way as well - I guess the mineral people in our house are just strange that way.

Anyone have an idea what this might be. It has been suggested that it is a romanechite cast of some iron mineral (goethite possibly). Any additional thoughts?


Unknown on Hemimorphite©


Thanks
Bob
avatar Re: Unknown from Ojuela Mine, Mexico
February 26, 2012 02:57AM
It could be a cast of some sort. Have you tried a streak test on the black mineral? It would be interesting and potentially diagnostic depending on the color.

Bob
Re: Unknown from Ojuela Mine, Mexico
February 26, 2012 10:42PM
    
I've seen that before and assumed it was partly dissolved (leached out) botryoids of goethite or hematite. What is left I assumed was some sort of iron oxide, but I guess it could be manganese oxides as well? Never did look into it very closely to try and figure out exactly what it is. Like most collectors I found the crystals on top of it more interesting.
Re: Unknown from Ojuela Mine, Mexico
February 27, 2012 02:48AM
    
Probably Limonite
avatar Re: Unknown from Ojuela Mine, Mexico
February 27, 2012 04:23AM
    
Bob - I agree with you, the back sides can be as interesting as the front. I can't count how many times I found the bottom or back sides of thumbnails more interesting than the front, only to be obscurred by that darn tack or worse, glued angry smiley .

In any case, that sure is a cool "matrix" and reminds me of a piece that Dana Slaughter has in the gallery also from Oujela, with a strange cast like formation. Perhaps Dana might have more insight on your piece and will chime in.

[www.mindat.org]
Author:

Your Email:


Subject:


Attachments:
  • 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.
CAPTCHA
Message:
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: September 21, 2014 12:03:30
Mineral and Locality Search
Mineral:
and/or Locality:
Options
Fade toolbar when not in focusFix toolbar to bottom of page
Hide Social Media Links
Slideshow frame delay seconds